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Timeline Of Biology And Organic Chemistry

Timeline of biology and organic chemistry

A Timeline of significant events in biology and organic chemistry

Before 1600

- c. 520 B.C. - Alcmæon of Croton distinguished veins from arteries and discovered the optic nerve.
- c. 500 B.C. - Sushruta - wrote Sushruta Samhita describing over 120 surgical instruments, 300 surgical procedures and classified human surgery in 8 categories. Performed cosmetic surgery.
- c. 500 B.C. - Xenophanes examined fossils and speculated on the evolution of life.
- c. 350 B.C. - Aristotle attempted a comprehensive classification of animals. His written works include Historia Animalium, a general biology of animals, De Partibus Animalium, a comparative anatomy and physiology of animals, and De Generatione Animalium, on developmental biology.
- c. 320 BC - Theophrastos (or Theophrastus) begins the systematic study of botany.
- c. 300 B.C. - Herophilos dissected the human body.
- c. 300 B.C. - Diocles wrote the first known anatomy book and was the first to use the term anatomy.
- c. 50-70 - Historia Naturalis by Pliny the Elder (Gaius Plinius Secundus) was published in 37 volumes.
- 130-200 - Claudius Galen wrote numerous treatises on human anatomy.
- c. 1010 - Avicenna (Ibn Sina or Abu Ali al Hussein ibn Abdallah) published his Canon of Medicine (Kitab al-Qanun fi al-tibb).

1600-1800

- 1628 - William Harvey publishes An Anatomical Exercise on the Motion of the Heart and Blood in Animals
- 1658 - Jan Swammerdam observes red blood cells under a microscope.
- 1663 - Robert Hooke sees cells in cork using a microscope.
- 1668 - Francesco Redi disproves theories of the spontaneous generation of maggots in putrefying matter.
- 1676 - Anton van Leeuwenhoek observes protozoa and calls them animalcules.
- 1677 - Anton van Leeuwenhoek observes spermatozoa.
- 1683 - Anton van Leeuwenhoek observes bacteria.
- 1765 - Lazzaro Spallanzani disproves many theories of the spontaneous generation of cellular life.
- 1771 - Joseph Priestley discovers that plants convert carbon dioxide into oxygen.
- 1798 - Thomas Malthus discusses human population growth and food production in An Essay on the Principle of Population.

1800-1899

- 1801 - Jean-Baptiste Lamarck begins the detailed study of invertebrate taxonomy.
- 1802 - The term biology in its modern sense is propounded independently by Gottfried Reinhold Treviranus (Biologie oder Philosophie der lebenden Natur) and Lamarck (Hydrogéologie). The word had been coined in 1800 by Karl Friedrich Burdach.
- 1809 - Lamarck proposes an inheritance of acquired characteristics theory of evolution.
- 1817 - Pierre-Joseph Pelletier and Joseph-Bienaime Caventou isolate chlorophyll.
- 1820 - Christian Friedrich Nasse formulates Nasse's law: hemophilia occurs only in males and is passed on by unaffected females.
- 1828 - Karl von Baer discovers the eggs of mammals.
- 1828 - Friedrich Woehler synthesizes urea; first synthesis of an organic compound from inorganic starting materials.
- 1836 - Theodor Schwann discovers pepsin in extracts from the stomach lining; first isolation of an animal enzyme.
- 1837 - Theodor Schwann shows that heating air will prevent it from causing putrefaction.
- 1838 - Matthias Schleiden discovers that all living plant tissue is composed of cells. ann discovers that all living animal tissue is composed of cells.
- 1856 - Louis Pasteur states that microorganisms produce fermentation.
- 1858 - Charles R. Darwin and Alfred Wallace independently propose natural selection. Only in later editions of his works did Darwin used the term "evolution," a philosophical principle coined by Herbert Spencer before 1852.
- 1858 - Rudolf Virchow proposes that cells can only arise from pre-existing cells.
- 1862 - Louis Pasteur convincingly disproves the spontaneous generation of cellular life.
- 1865 - Gregor Mendel presents his experiments on the crossbreeding of pea plants and postulates dominant and recessive factors.
- 1865 - Friedrich August Kekulé von Stradonitz realizes that benzene is composed of carbon and hydrogen atoms in a hexagonal ring.
- 1869 - Friedrich Miescher discovers nucleic acids in the nuclei of cells.
- 1874 - Jacobus van 't Hoff and Joseph-Achille Le Bel advance a three-dimensional stereochemical representation of organic molecules and propose a tetrahedral carbon atom.
- 1876 - Oskar Hertwig and Hermann Fol show that fertilized eggs possess both male and female nuclei.
- 1884 - Emil Fischer begins his detailed analysis of the compositions and structures of sugars.
- 1898 - Martinus Beijerinck uses filtering experiments to show that tobacco mosaic disease is caused by something smaller than a bacteria which he names a virus.

1900-1949

- 1906 - Mikhail Tsvet discovers the chromatography technique for organic compound separation.
- 1907 - Ivan Pavlov demonstrates conditioned responses with salivating dogs.
- 1907 - Emil Fischer artificially synthesizes peptide amino acid chains and thereby shows that amino acids in proteins are connected by amino group-acid group bonds.
- 1911 - Thomas Morgan proposes that Mendelian factors are arranged in a line on chromosomes.
- 1926 - James Sumner shows that the urease enzyme is a protein.
- 1928 - Otto Diels and Kurt Alder discover the Diels-Alder cycloaddition reaction for forming ring molecules.
- 1928 - First antibiotic, penicillin, discovered by Alexander Fleming
- 1929 - Phoebus Levene discovers the sugar deoxyribose in nucleic acids.
- 1929 - Edward Doisy and Adolf Butenandt independently discover estrone.
- 1930 - John Howard Northrop shows that the pepsin enzyme is a protein.
- 1931 - Adolf Butenandt discovers androsterone.
- 1932 - Hans Adolf Krebs discovers the urea cycle.
- 1933 - Tadeus Reichstein artificially synthesizes vitamin C; first vitamin synthesis.
- 1935 - Rudolf Schoenheimer uses deuterium as a tracer to examine the fat storage system of rats.
- 1935 - Wendell Stanley crystallizes the tobacco mosaic virus.
- 1935 - Konrad Lorenz describes the imprinting behavior of young birds.
- 1937 - Hans Adolf Krebs discovers the tricarboxylic acid cycle.
- 1937 - Theodosius Dobzhansky links evolution and genetic mutation in Genetics and the Origin of Species.
- 1938 - A living coelacanth is found off the coast of southern Africa.
- 1940 - Donald Griffin and Robert Galambos announce their discovery of sonar echolocation by bats.
- 1942 - Max Delbruck and Salvador Luria demonstrate that bacterial resistance to virus infection is caused by random mutation and not adaptive change.
- 1944 - Oswald Avery shows that DNA carries the genetic code in pneumococci bacteria.
- 1944 - Robert Woodward and William von Eggers Doering synthesize quinine.
- 1948 - Erwin Chargaff shows that in DNA the number of guanine units equals the number of cytosine units and the number of adenine units equals the number of thymine units.

1950-1989

- 1951 - Robert Woodward synthesizes cholesterol and cortisone.
- 1952 - Alfred Hershey and Martha Chase use radioactive tracers to show that DNA is the genetic material in bacteriophage viruses.
- 1952 - Fred Sanger, Hans Tuppy, and Ted Thompson complete their chromatographic analysis of the insulin amino acid sequence.
- 1952 - Rosalind Franklin uses X-ray diffraction to study the structure of DNA and suggests that its sugar-phosphate backbone is on its outside.
- 1953 - James D. Watson and Francis Crick propose a double helix structure for DNA.
- 1953 - Max Perutz and John Kendrew determine the structure of hemoglobin using X-ray diffraction studies.
- 1953 - Stanley Miller shows that amino acids can be formed when simulated lightning is passed through vessels containing water, methane, ammonia, and hydrogen.
- 1955 - Severo Ochoa discovers RNA polymerase enzymes.
- 1955 - Arthur Kornberg discovers DNA polymerase enzymes.
- 1960 - Juan Oro finds that concentrated solutions of ammonium cyanide in water can produce the nucleotide organic base adenine.
- 1960 - Robert Woodward synthesizes chlorophyll.
- 1967 - John Gurden uses nuclear transplantation to clone a clawed frog; first cloning of a vertebrate.
- 1968 - Fred Sanger uses radioactive phosphorus as a tracer to chromatographically decipher a 120 base long RNA sequence.
- 1970 - Hamilton Smith and Daniel Nathans discover DNA restriction enzymes.
- 1970 - Howard Temin and David Baltimore independently discover reverse transcriptase enzymes.
- 1972 - Robert Woodward synthesizes vitamin B-12.
- 1972 - Stephen Jay Gould and Niles Eldredge propose punctuated equilibrium effects in evolution.
- 1972 - SJ Singer and GL Nicholson develop the fluid mosaic model, which deals with the make-up of the membrane of all cells.
- 1974 - Manfred Eigen and Manfred Sumper show that mixtures of nucleotide monomers and RNA replicase will give rise to RNA molecules which replicate, mutate, and evolve.
- 1974 - Leslie Orgel shows that RNA can replicate without RNA-replicase and that zinc aids this replication.
- 1977 - John Corliss, Jack Dymond, Louis Gordon, John Edmond, Richard von Herzen, Robert Ballard, Kenneth Green, David Williams, Arnold Bainbridge, Kathy Crane, and Tjeerd van Andel discover chemosynthetically based animal communities located around submarine hydrothermal vents on the Galapagos Rift.
- 1977 - Walter Gilbert and Allan Maxam present a rapid gene sequencing technique which uses cloning, base destroying chemicals, and gel electrophoresis.
- 1977 - Frederick Sanger and Alan Coulson present a rapid gene sequencing technique which uses dideoxynucleotides and gel electrophoresis.
- 1978 - Frederick Sanger presents the 5,386 base sequence for the virus PhiX174; first sequencing of an entire genome.
- 1982 - Concept of prions introduced by Stanley B. Prusiner
- 1983 - Kary Mullis invents the polymerase chain reaction.
- 1984 - Alec Jeffreys devises a genetic fingerprinting method.
- 1985 - Harry Kroto, J.R. Heath, S.C. O'Brien, R.F. Curl, and Richard Smalley discover the unusual stability of the buckminsterfullerene molecule and deduce its structure.
- 1986 - Alexander Klibanov demostrates that enzymes can function in non-aqueous environments.

1990-present

- 1990 - Wolfgang Krätschmer, Lowell Lamb, Konstantinos Fostiropoulos, and Donald Huffman discover that Buckminsterfullerene can be separated from soot because it is soluble in benzene.
- 1996 - Dolly the sheep is first clone of an adult mammal.
- 2001 - Publication of the first drafts of the complete human genome.
- 2003 - First virus produced 'from scratch'.

Footnote

The date at which the Sushruta Samhita was compiled is uncertain. [http://www.atributetohinduism.com/Hindu_Culture2.htm A Tribute to Hinduism] says Sushruta lived in the 5th century B.C., and so the date 500 B.C. may be too early. Biology and Organic chemistry

Timeline

:Alternative meanings: :
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External links

History

- [http://worldhistorytimeline.net/en Timeline Wall Chart of Evolution, Culture and Knowledge: 13,7 billion years of history]
- [http://www.hyperhistory.com/online_n2/History_n2/a.html HyperHistory Oneline: a scientific project presenting 3,000 years of world history with an interactive combination of synchronoptic lifelines, timelines, and maps]
- [http://coombs.anu.edu.au/asian-studies-timeline.html Asian Studies online: a timeline of major developments]
- [http://www.ciolek.com/PAPERS/milestones.html Global networking: a timeline]
- [http://timelines.ws/ Timelines of History: a collection of timelines by time, country, today in history along with assorted subjects]
- [http://www.moviestimeline.com/ Interactive/editable movie timeline 1900-Present Day]
- [http://www.earlham.edu/~peters/fos/timeline.htm Timeline of the open access movement]
- [http://whenswho.redgolpe.com When's who: a timeline of history makers]
- [http://www.twoop.com Twoop] An interlinked timeline project

Fiction

- [http://www.mts.net/~arphaxad/history.html List of timelines from across the web of things that never were]
- [http://moa.dracandros.com/ Fictional encyclopedia wiki with a section for fictional history]
- [http://mycgiserver.com/~burnsanthony/manifesto/easytimeline.html Make your own timeline]
- [http://www.timelineindex.com List of timelines sorted in categories] Themed timelines Category:Timelines ja:年表一覧

Vein

:In geology, a vein is a regularly shaped and lengthy occurrence of an ore; a lode. In biology, a vein is a blood vessel which returns blood from the microvasculature to the heart. Veins form part of the circulatory system. The vessels carrying blood away from the heart are known as arteries.

Biological Vein

Veins have one-way valves to prevent backflow caused by gravity. arteries In systemic circulation de-oxygenated blood from the capillary blood vessels is taken by veins to the right part of the heart. Differently, in the pulmonary circulation oxygenated blood from the lungs is taken to the left part of the heart by pulmonary veins. Another special case is portal circulation where the portal vein transports blood rich in products of digestion from the intestines to the liver. Names of important veins:
- Pulmonary veins
- Portal vein
- Superior vena cava
- Inferior vena cava
- Femoral vein
- Great saphenous vein Veins are used medically as points of access to the blood stream, permitting the withdrawal of blood specimens (venipuncture) for testing purposes, and enabling the infusion of fluid, electrolytes, nutrition, and medications. The latter is called intravenous delivery. It can be done by an injection with a syringe, or by inserting a catheter (a flexible tube). If an intravenous catheter has to be inserted, for most purposes this is done into a peripheral vein (a vein near the surface of the skin in the hand or arm, or less desirably, the leg.) Some highly concentrated fluids or irritating medications must flow into the large central veins, which are sometimes used when peripheral access cannot be obtained. Catheters can be threaded into the superior vena cava for these uses: if long term use is thought to be needed, a more permanent access point can be inserted surgically. The precise location of veins is much more variable from person to person than that of arteries.

Optic nerve

The optic nerve is the nerve that transmits visual information from the retina to the brain.

Anatomy

The optic nerve is the second of twelve paired cranial nerves but is considered to be part of the central nervous system as it is derived from an outpouching of the diencephalon during embryonic development. Consequently, the fibers are covered with myelin produced by oligodendrocytes rather than the Schwann cells of the peripheral nervous system. This is an important issue, as fiber tracks of the mammalian central nervous system (as opposed to the peripheral nervous system) are incapable of regeneration and hence optic nerve damage produces irreversible blindness. The fibers from the retina run along the optic nerve to nine primary visual nuclei in the brain, from whence a major relay inputs into the primary visual cortex. primary visual cortex The optic nerve is composed of retinal ganglion cell axons and support cells. It leaves the orbit (eye) via the optic canal, running postero-medially towards the optic chiasm where there is a partial decussation (crossing) of fibers from the temporal visual fields of both eyes. Most of the axons of the optic nerve terminate in the lateral geniculate nucleus from where information is relayed to the visual cortex. Its diameter increases from about 1.6 mm within the eye, to 3.5 mm in the orbit to 4.5 mm within the cranial space. The optic nerve component lengths are 1mm in the globe, 25mm in the orbit, 9mm in the optic canal and 16mm in the cranial space before joining the optic chiasm. There, partial decussation occurs and about 53% of the fibers cross to form the optic tracts. Most of these fibers terminate in the lateral geniculate body. From the lateral geniculate body, fibers of the optic radiation pass to the visual cortex in the occipital lobe of the brain. More specifically, fibers carrying information from the contralateral superior visual field traverse Meyer's loop to terminate in the lingual gyrus below the calcarine fissure in the occipital lobe, and fibers carrying information from the contralateral inferior visual field terminate more superiorly.

Physiology

The optic nerve contains 1.2 million nerve fibers. This number is low compared to the roughly 130 million receptors in the retina, and implies that substantial pre-processing takes place in the retina before the signals are sent to the brain through the optic nerve. The blind spot of the eye is produced by the absence of retina where the optic nerve leaves the eye. This is because there are no photoreceptors in this area.

Role in disease

Damage to the optic nerve typically causes permanent and potentially severe loss of vision, as well as an abnormal pupillary reflex, which is diagnostically important. The type of visual field loss will depend on which portions of the optic nerve were damaged. Generally speaking:
- Damage before the optic chiasm causes loss of vision in the visual field of the same side only.
- Damage in the chiasm causes loss of vision laterally in both visual fields (bitemporal hemianopia). It may occur in large pituitary adenomata.
- Damage after the chiasm causes loss of vision on one side but affecting both visual fields: the visual field affected is located on the opposite side of the lesion. Injury to the optic nerve can be the result of congenital or inheritable problems like Leber's Hereditary Optic Neuropathy, glaucoma, trauma, toxicity, inflammation, ischemia, infection (very rarely), or compression from tumors or aneurysms. By far, the three most common injuries to the optic nerve are from glaucoma, optic neuritis (especially in those younger than 50 years of age) and anterior ischemic optic neuropathy (usually in those older than 50). Glaucoma is a group of diseases involving loss of retinal ganglion cells causing optic neuropathy in a pattern of peripheral vision loss, initially sparing central vision. Optic neuritis is inflammation of the optic nerve. It is associated with a number of diseases, most notably multiple sclerosis. Anterior Ischemic Optic Neuropathy is a particular type of infarct that affects patients with an anatomical predisposition and cardiovascular risk factors. Ophthalmologists, particularly those subspecialists who are neuro-ophthalmologists, are often best suited to diagnose and treat diseases of the optic nerve.

External links

- [http://www.med.harvard.edu/AANLIB/cases/caseM/mr1_t/023.html The optic nerve on MRI] Category:Visual system Category:Cranial nerves ja:視神経

Sushruta

Sushruta was an ancient Indian surgeon (datable to between the 2nd century BCE and about the 2nd century CE) and is the author of the book Sushruta Samhita, in which he describes over 120 surgical instruments, 300 surgical procedures and classifies human surgery in 8 categories. In the Sushruta school, the first person to expound Āyurvedic knowledge was Dhanvantari who then taught it to Divodasa who, in turn, taught it to Sushruta, Aupadhenava, Aurabhra, Paushakalāvata, Gopurarakshita, and Bhoja. He is credited with performing cosmetic surgery and especially with using forehead skin to reconstruct noses which were amputated as a punishment for crimes in his era.

External links

- [http://www.infinityfoundation.com/mandala/t_es/t_es_agraw_susruta.htm Susruta the great surgeon of yore]
- [http://www.ijps.org/article.asp?issn=0970-0358;year=2003;volume=36;issue=1;spage=4;epage=13;aulast=Chari Susruta and our heritage]
- [http://vigyanprasar.com/dream/jan2000/article2.htm Plastic Surgery in India]
- [http://www.jpgmonline.com/article.asp?issn=0022-3859;year=2002;volume=48;issue=1;spage=76;epage=8;aulast=Rana History of Plastic Surgery in India] Category:Indian surgeons Category:Ayurveda

Xenophanes

Xenophanes of Colophon (570 BC-480 BC) was a Greek philosopher, poet, and social and religious critic. Our knowledge of his views comes from his surviving poetry, all of which are fragments passed down as quotations by later Greek writers. His poetry criticized and satirized a wide range of ideas, including the belief in the pantheon of anthropomorphic gods and the Greeks' veneration of athleticism. Xenophanes rejected the then-standard belief in many gods, as well as the idea that the gods resembled humans in form. One famous passage ridiculed the idea by claiming that, if oxen were able to imagine gods, then those gods would be in the image of oxen. Because of his development of the concept of One God that is abstract, universal, unchanging, immobile and always present, Xenophanes is often seen as one of the first monotheists in the Western philosophy of religion. He also wrote that poets should only tell stories about the gods which were socially uplifting, one of many views which foreshadowed the work of Plato. Xenophanes also concluded from his examination of fossils that water once must have covered all of the Earth's surface. His epistemology, which is still influential today, held that there actually exists a truth of reality, but that humans as mortals are unable to know it. Therefore, it is possible to act only on the basis of working hypotheses - we may act as if we knew the truth, as long as we know that this is extremely unlikely. This aspect of Xenophanes was brought out again by the late Sir Karl Popper and is a basis of Critical rationalism. Until the 1950s, there was some controversy over many aspects of Xenophanes, including whether or not he could be properly characterized as a philosopher. In today's philosophical and classics discourse, Xenophanes is seen as one of the most important presocratic philosophers. It had also been common to see him as the teacher of Zeno of Elea, the colleague of Parmenides, and generally associated with the Eleatic school, but common opinion today is likewise that this is false.

Bibliography

Editions

- H. Diels and W. Kranz (eds.), Die Fragmente der Vorsokratiker, 6th edn. Zurich 1968 (standard work; much superior to Kirk/Raven)
- B. Gentili and C. Prato (eds.), Poetarum Elegiacorum Testimonia et Fragmenta 1, Leipzig 1988 (best Greek text available)
- J.H. Lesher (ed.), Xenophanes. Fragments, Toronto 1992 (best English edition and translation)

Secondary Literature

- [http://ablemedia.com/ctcweb/showcase/deyoung1.html U. De Young, "The Homeric Gods and Xenophanes' Opposing Theory of the Divine", 2000]
- W. Drechsler and R. Kattel, "Mensch und Gott bei Xenophanes", in: M. Witte, ed., Gott und Mensch im Dialog. Festschrift für Otto Kaiser zum 80. Geburtstag, Berlin – New York 2004, 111-129
- H. Fränkel, "Xenophanesstudien", Hermes 60 (1925), 174-192
- E. Heitsch, Xenophanes und die Anfänge kritischen Denkens. Mainzer Akademie der Wissenschaften und der Literatur, Abh. d. Geistes- und Sozialwiss. Kl., 1994, H. 7
- W. Jaeger, The Theology of the Early Greek Philosophers, Gifford Lectures 1936, repr. Westport, Ct. 1980
- K. Jaspers, The Great Philosophers 3, New York etc. 1993
- R. Kattel, "The Political Philosophy of Xenophanes of Colophon", Trames 1(51/46) (1997), 125-142
- O. Kaiser, "Der eine Gott und die Götter der Welt", in: Zwischen Athen und Jerursalem. Studien zur griechischen und biblischen Theologie, ihrer Eigenart und ihrem Verhältnis, Berlin - New York 2003, 135-152
- K. Ziegler, "Xenophanes von Kolophon, ein Revolutionär des Geistes", Gymmasium 72 (1965), 289-302

External links

- [http://plato.stanford.edu/entries/xenophanes/ Stanford Encyclopedia of Philosophy entry] Category:570 BC births Category:480 BC deaths Category:Presocratic philosophers Category:Ancient Greek philosophers Category:Ancient Greek poets ja:クセノパネス

Fossil

:For other uses of the term, see Fossil (disambiguation) Fossil (disambiguation)] Fossils are the mineralized or otherwise preserved remains -- or other traces (such as footprints) -- of animals, plants, and other organisms. The totality of fossils and their placement in fossiliferous (fossil-containing) rock formations and sedimentary layers (strata) is known as the fossil record. The study of fossils is called paleontology. The word fossil is derived from the Latin word fossus, which means "having been dug up". Latin Fossilization is actually a rare occurrence because natural materials tend to decompose. In order for an organism to be fossilized, the remains normally need to be covered by sediment as soon as possible. However there are exceptions to this, such as if an organism becomes petrified or comes to rest in an anoxic environment such as at the bottom of a lake. There are several different types of fossils and fossilization processes. Fossils usually consist of traces of the remains of the organism itself. However, fossils may also consist of the marks left behind by the organism while it was alive, such as the footprint or feces of a dinosaur or reptile. These types of fossil are called trace fossils, as opposed to body fossils. Finally, past life leaves some evidences that cannot be seen but can be detected in the form of chemical signals; these are known as chemical fossils (for lack of a better term). trace fossil The oldest known structured fossils are most likely stromatolites. Now understood to be formed by the entrapment of minerals by mucous-like sheets of cyanobacteria, the oldest of these formations dates from 3.5 billion years ago. Even older deposits (3.8 billion years old) of heavy carbon that are indicative of even earlier life are currently proposed as the remains of the earliest known life on Earth.

Permineralization

Earth]] Permineralization consists of organic remains being to some degree impregnated by minerals derived from the surrounding sediments or waters. For permineralization to occur, the organism must become covered by sediment soon after death or soon after the initial decaying process. The degree to which the remains are decayed when covered determines the later details of the fossil. Some fossils consist only of skeletal remains or teeth; other fossils contain traces of skin, feathers or even soft tissues. Once covered with sediment, these layers slowly become compacted and cemented into rock, and the organic remains are slowly replaced with hard minerals.

Replacement and compression fossils

In some cases the original remains of the organism have been completely dissolved or otherwise destroyed. When all that is left is an organism-shaped hole in the rock, we call this a mould fossil or typolite. If this hole is later filled with other minerals, it is called a cast fossil and is considered a replacement fossil since the original materials have been completely replaced by new, unrelated ones. In some cases replacement occurs so gradually and at such fine scales that no "hole" in the rock can ever be discerned and microstructural features are preserved despite the total loss of original material. Compression fossils such as those of fossil ferns are the result of chemical reduction of the complex organic molecules composing the organism's tissues. In this case the fossil consists of original material, albeit in a geochemically altered state. To sum up, fossilization processes proceed differently for different kinds of tissues and under different kinds of conditions.

Trace fossils

Trace fossils are the remains of trackways, burrows, footprints, eggs and egg-shells, nests, and droppings (among other types of impressions). Fossilized droppings, called coprolites, can give insight into the feeding behavior of animals and can therefore be of great importance.

Resin fossils

Smaller animals, such as insects, spiders and small lizards, can be trapped in resin (amber), which is secreted from trees. These fossils can be found in sandstones or mudstones or washed up on beaches like those around the Baltic Sea.

Pseudofossils

Baltic Sea Pseudofossils are visual patterns in rocks that are produced by naturally occurring geologic processes rather than biologic processes. They can easily be mistaken for real fossils. Some pseudofossils, such as dendrites, are formed by naturally occurring fissures in the rock that get filled up by percolating minerals. Other types of pseudofossils are kidney ore (round shapes in iron ore) and moss agates, which look like moss or plant leaves. Concretions, round or oval-shaped nodules found in some sedimentary strata, were once thought to be dinosaur eggs, and are often mistaken for fossils as well.

Living fossils

Living fossil is a term used for any living species which closely resembles a species known from fossils, i.e., as if the fossil had "come to life". This can be a species known only from fossils until living representatives were discovered, such as the coelacanth and the ginkgo tree, or a single living species with no close relatives, such as the horseshoe crab, that is the sole survivor of a once large and widespread group in the fossil record.

External links

- [http://www.fossilmuseum.net/index.htm The Virtual Fossil Museum throughout Time and Evolution] Category:Paleontology ko:화석 ja:化石 simple:Fossil th:ซากดึกดำบรรพ์

Life

:For other uses, see Life and Living Life is a multi-faceted concept. Life may refer to the ongoing process of which living things are a part, the period between the conception (or a point at which the entity can be considered to be an individualized being) and death of an organism, the condition of an entity that has been born (or reached the point in its existence at which it can be established to be alive) and has yet to die, and that which makes a living thing alive.

Defining the concept of life

How can one tell when an entity is a lifeform? It would be relatively straightforward to offer a practical set of guidelines if one's only concern were life on Earth as we know it (see biosphere), but as soon as one considers questions about life's origins on Earth, or the possibility of extraterrestrial life, or the concept of artificial life, it becomes clear that the question is fundamentally difficult and comparable in many respects to the problem of defining intelligence. Also, loosely speaking, some theories are grounded in the basic assumption that "ideas have a life of their own".

A conventional definition

In biology, a lifeform has traditionally been considered to be a member of a population whose members can exhibit all the following phenomena at least once during their existence: #Growth, full development, maturity #Metabolism, consuming, transforming and storing energy/mass; growing by absorbing and reorganizing mass; excreting waste #Motion, either moving itself, or having internal motion #Reproduction, the ability to create entities that are similar to, yet separate from, itself or consisting solely of entities that exhibit the quality of reproduction. #Response to stimuli - the ability to measure properties of its surrounding environment, and act upon certain conditions. This property is also called homeostasis.

Exceptions to the conventional definition

These criteria are not without their uses, but their disparate nature makes them unsatisfactory from a number of perspectives; in fact, it is not difficult to find counterexamples and examples that require further elaboration. For example, according to the above definition, one could say:
- (most) mules and people who are infertile cannot reproduce and thus would not qualify as lifeforms. Also worker bees and other organisms living in colonies would not qualify; only the queen and the drones (or the whole colony) can be considered 'alive'.
- Fire and stars could be considered lifeforms.
- A virus does not grow and cannot reproduce outside of a host cell and thus would not qualify as a lifeform. Many individual organisms are incapable of reproduction and yet are still considered to be lifeforms; see mules and ants for examples. This is because the term "lifeform" applies on the level of entire species or of individual genes. (For example, see kin selection for information about one way by which non-reproducing individuals can still enhance the spread of their genes and the survival of their species.) It is important to keep in mind the difference between a "lifeform" and "a being that is alive." One example of sterility does not render the rest of the species a non-lifeform, any more than one dead animal renders the rest of the species dead. Note also that the two cases of fire and stars fitting the definition of life can be simply remedied by defining metabolism in a more biochemically exact way. Fundamentals of Biochemistry by Donald Voet and Judith Voet (ISBN 0471586501) defines metabolism as follows: "Metabolism is the overall process through which living systems acquire and utilize the free energy they need to carry out their various functions. They do so by coupling the exergonic reactions of nutrient oxidation to the endergonic processes required to maintain the living state, such as the performance of mechanical work, the active transport of molecules against concentration gradients, and the biosynthesis of complex molecules." This definition, in use by most biochemists, makes it clear that fire is not alive, because fire releases all the oxidative energy of its fuel as heat. (Note: Actually, the definition does not help much at all, for it is circular. What we are looking for, after all, is a definition of "living entity." We agreed that part of the definition is "capable of metabolism." We then tried to define "metabolism" in order to get clear on which entities are capable of it and which not. But the definition of "metabolism" just offered is in terms of living systems, and those are exactly what we are trying to define!) This could also be remedied by adding the requirement of locality, where there is an obvious structure that delineates the spatial extension of the living being, such as a cell membrane. A conceptual problem with saying that fire is life is that it collapses the distinction between "growth" and "reproduction." It is possible to think of a spreading flame as either growing or reproducing, but what would it mean to say that the same act is both growth and reproduction? Viruses reproduce, flames grow, some software programs mutate and evolve, future software programs will probably evince (even high-order) behavior, machines move, and some form of proto-life consisting of metabolizing cells without the ability to reproduce presumably existed. Still, some would not call these entities alive. Generally, all five characteristics are required for a population to be considered a lifeform.

Other definitions

Biologists who are content to focus on terrestrial organisms often note some additional signs of life, including these: # Living organisms contain molecular components such as: carbohydrates, lipids, nucleic acids, and proteins. # Living organisms require both energy and matter in order to continue living. # Living organisms are composed of at least one cell. # Living organisms maintain homeostasis for some period of time. # Species of living organisms will evolve. All life on Earth is based on the chemistry of carbon compounds. Some assert that this must be the case for all possible forms of life throughout the universe; others describe this position as 'carbon chauvinism'. The systemic definition is that living things are self-organizing and autopoietic (self-producing). These objects are not to be confused with dissipative structures (e.g. fire). Variations of this definition include:
- Francisco Varela and Humberto Maturana's definition of life (also widely used by Lynn Margulis) as an autopoietic (self-producing), water based, lipid-protein bound, carbon metabolic, nucleic acid replicated, protein readout system
- "a system of inferior negative feedbacks subordinated to a superior positive feedback" ([http://www.mol.uj.edu.pl/~benio/cyber_def_life.pdf J. theor Biol. 2001])
- Tom Kinch's definition of life as a highly organized auto-cannibalizing system naturally emerging from conditions common on planetary bodies, and consisting of a population of replicators capable of mutation, around each set of which a homeostatic metabolizing organism, which actively helps reproduce and/or protect the replicator(s), has evolved
- Stuart Kauffman's definition of life as an autonomous agent or a multi-agent system capable of reproducing itself or themselves, and of completing at least one thermodynamic work cycle
- Robert Pirsig's definition of life, found in his book Lila: An Inquiry into Morals, as that which maximizes its range of possible futures, in other words, that which makes decisions that result in the most future choices, or that which strives to keep its options open.
- A system converting entropy to negentropy, using flow of energy. Other definitions:
- That which seeks to continue its own existence (attributed to Clifford A. Schaffer).
- A self-replicating system that evolves through mutation.

Descent with modification: a "useful" characteristic

A useful characteristic upon which to base a definition of life is that of descent with modification: the ability of a life form to produce offspring that are like its parent or parents, but with the possibility of some variation due to chance. Descent with modification is sufficient by itself to allow evolution, assuming that the variations in the offspring allow for differential survival. The study of this form of heritability is called genetics. In all known life forms (assuming prions are not counted as such), the genetic material is primarily DNA or the related molecule, RNA. Another exception might be the software code of certain forms of viruses and programs created through genetic programming, but whether computer programs can be alive even by this definition is still a matter of some contention.

Origin of life

Main article: Origin of life There is no truly "standard" model of the origin of life, but most currently accepted scientific models build in one way or another on the following discoveries, which are listed roughly in order of postulated emergence: #Plausible pre-biotic conditions result in the creation of the basic small molecules of life. This was demonstrated in the Urey-Miller experiment. #Phospholipids spontaneously form lipid bilayers, the basic structure of a cell membrane. #Procedures for producing random RNA molecules can produce ribozymes, which are able to produce more of themselves under very specific conditions. There are many different hypotheses regarding the path that might have been taken from simple organic molecules to protocells and metabolism. Many models fall into the "genes-first" category or the "metabolism-first" category, but a recent trend is the emergence of hybrid models that do not fit into either of these categories.

The possibility of extraterrestrial life

Main articles: Extraterrestrial life, Astrobiology As of 2005, Earth is the only planet in the universe known by humans to support life. The question of whether life exists elsewhere in the universe remains open, but analyses such as the Drake equation have been used to estimate the probability of such life existing. There have been a number of claims of the discovery of life elsewhere in the universe, but none of these have yet survived scientific scrutiny. Today, the closest that scientists have come to finding extraterrestrial life is fossil evidence of possible bacterial life on Mars (via the ALH84001 meteorite). Searches for extraterrestrial life are currently focusing on planets and moons believed to possess liquid water, at present or in the past. Recent evidence from the NASA rovers Spirit and Opportunity supports the theory that Mars once had surface water. See Life on Mars for further discussion. Jupiter's moons are also considered good candidates for extraterrestrial life, especially Europa, which seems to possess oceans of liquid water. Other highly speculative and somewhat doubtful places for present or past life include the atmosphere of Venus, Titan cryovolcanoes, or even Enceladus.

References

- Kauffman, Stuart. The Adjacent Possible: A Talk with Stuart Kauffman. Retrieved Nov. 30, 2003 from [http://www.edge.org/3rd_culture/kauffman03/kauffman_index.html]

External links

- [http://www.lifetheory.com Express your theory and meaning of life]
- [http://www.edge.org/3rd_culture/kauffman03/kauffman_index.html "The Adjacent Possible: A Talk with Stuart Kauffman"]
- [http://www.quotesandpoem.com/poems/SelectedPoetryTopic/Life Poems and Quotes about life and living]
- [http://www.angelfire.com/linux/vjtorley/ Animals and other living things: their interests, mental capacities and moral entitlements]
- [http://tolweb.org/tree?group=life Tree of Life Web Project - Life on Earth]
- [http://plato.stanford.edu/entries/life/ Stanford Encyclopedia of Philosophy entry]
- [http://web.archive.org/web/20041030074958/http://people.cornell.edu/pages/tg21/DHB.html The Deep Hot Biosphere Theory (Thomas Gold)] Category:Biology ja:生命 ko:생명 ms:Benda hidup simple:Life

Aristotle

by Lysippos. Louvre Museum.]] Aristotle (Greek: Αριστοτέλης Aristotelēs; 384 BC – March 7, 322 BC) was an ancient Greek philosopher, student of Plato and teacher of Alexander the Great. He wrote many books about physics, poetry, zoology, logic, rhetoric, government, and biology. Aristotle, along with Plato and Socrates, is generally considered one of the most influential ancient Greek philosophers in Western thought. Among them they transformed Presocratic Greek philosophy into the foundations of Western philosophy as we know it. The writings of Plato and Aristotle form the core of Ancient philosophy. Aristotle placed much more value on knowledge gained from the senses and would correspondingly be better classed among modern empiricists (see materialism and empiricism). He also achieved a "grounding" of dialectic in the Topics by allowing interlocutors to begin from commonly held beliefs (Endoxa); his goal being non-contradiction rather than Truth. He set the stage for what would eventually develop into the scientific method centuries later. Although he wrote dialogues early in his career, no more than fragments of these have survived. The works of Aristotle that still exist today are in treatise form and were, for the most part, unpublished texts. These were probably lecture notes or texts used by his students, and were almost certainly revised repeatedly over the course of years. As a result, these works tend to be eclectic, dense and difficult to read. Among the most important ones are Physics, Metaphysics, Nicomachean Ethics, Politics, De Anima (On the Soul) and Poetics. Their works, although connected in many fundamental ways, are very different in both style and substance. Aristotle is known for being one of the few figures in history who studied almost every subject possible at the time. In science, Aristotle studied anatomy, astronomy, embryology, geography, geology, meteorology, physics, and zoology. In philosophy, Aristotle wrote on aesthetics, economics, ethics, government, metaphysics, politics, psychology, rhetoric and theology. He also dealt with education, foreign customs, literature and poetry. His combined works practically comprise an encyclopedia of Greek knowledge.

Biography

Early life and studies at the Academy

encyclopedia.]] Aristotle was born at Stageira, a colony of Andros on the Macedonian peninsula of Chalcidice in 384 BC. His father, Nicomachus, was court physician to King Amyntas III of Macedon. It is believed that Aristotle's ancestors held this position under various kings of Macedonia. As such, Aristotle's early education would probably have consisted of instruction in medicine and biology from his father. About his mother, Phaestis, little is known. It is known that she died early in Aristotle's life. When Nicomachus also died, in Aristotle's tenth year, he was left an orphan and placed under the guardianship of his uncle, Proxenus of Atarneus. He taught Aristotle Greek, rhetoric, and poetry (O'Connor et al., 2004). Aristotle was probably influenced by his father's medical knowledge; when he went to Athens at the age of 18, he was likely already trained in the investigation of natural phenomena. From the age of 18 to 37 Aristotle remained in Athens as a pupil of Plato and distinguished himself at the Academy. The relations between Plato and Aristotle have formed the subject of various legends, many of which depict Aristotle unfavourably. No doubt there were divergences of opinion between Plato, who took his stand on sublime, idealistic principles, and Aristotle, who even at that time showed a preference for the investigation of the facts and laws of the physical world. It is also probable that Plato suggested that Aristotle needed restraining rather than encouragement, but not that there was an open breach of friendship. In fact, Aristotle's conduct after the death of Plato, his continued association with Xenocrates and other Platonists, and his allusions in his writings to Plato's doctrines prove that while there were conflicts of opinion between Plato and Aristotle, there was no lack of cordial appreciation or mutual forbearance. Besides this, the legends that reflect Aristotle unfavourably are traceable to the Epicureans, who were known as slanderers. If such legends were circulated widely by patristic writers such as Justin Martyr and Gregory Nazianzen, the reason lies in the exaggerated esteem Aristotle was held in by the early Christian heretics, not in any well-grounded historical tradition.

Aristotle as philosopher and tutor

After the death of Plato (347 BC), Aristotle was considered as the next head of the Academy, a post that was eventually awarded to Plato's nephew. Aristotle then went with Xenocrates to the court of Hermias, ruler of Atarneus in Asia Minor, and married his niece and adopted daughter, Pythia. In 344 BC, Hermias was murdered in a rebellion, and Aristotle went with his family to Mytilene. It is also reported that he stopped on Lesbos and briefly conducted biological research. Then, one or two years later, he was summoned to Pella, the Macedonian capital, by King Philip II of Macedon to become the tutor of Alexander the Great, who was then 13. Plutarch wrote that Aristotle not only imparted to Alexander a knowledge of ethics and politics, but also of the most profound secrets of philosophy. We have much proof that Alexander profited by contact with the philosopher, and that Aristotle made prudent and beneficial use of his influence over the young prince (although Bertrand Russell disputes this). Due to this influence, Alexander provided Aristotle with ample means for the acquisition of books and the pursuit of his scientific investigation. It is possible that Aristotle also participated in the education of Alexander's boyhood friends, which may have included for example Hephaestion and Harpalus. Aristotle maintained a long correspondence with Hephaestion, eventually collected into a book, unfortunately now lost. According to sources such as Plutarch and Diogenes, Philip had Aristotle's hometown of Stageira burned during the 340s BC, and Aristotle successfully requested that Alexander rebuild it. During his tutorship of Alexander, Aristotle was reportedly considered a second time for leadership of the Academy; his companion Xenocrates was selected instead.

Founder and master of the Lyceum

In about 335 BC, Alexander departed for his Asiatic campaign, and Aristotle, who had served as an informal adviser (more or less) since Alexander ascended the Macedonian throne, returned to Athens and opened his own school of philosophy. He may, as Aulus Gellius says, have conducted a school of rhetoric during his former residence in Athens; but now, following Plato's example, he gave regular instruction in philosophy in a gymnasium dedicated to Apollo Lyceios, from which his school has come to be known as the Lyceum. (It was also called the Peripatetic School because Aristotle preferred to discuss problems of philosophy with his pupils while walking up and down -- peripateo -- the shaded walks -- peripatoi -- around the gymnasium). During the thirteen years (335 BC–322 BC) which he spent as teacher of the Lyceum, Aristotle composed most of his writings. Imitating Plato, he wrote Dialogues in which his doctrines were expounded in somewhat popular language. He also composed the several treatises (which will be mentioned below) on physics, metaphysics, and so forth, in which the exposition is more didactic and the language more technical than in the Dialogues. These writings show to what good use he put the resources Alexander had provided for him. They show particularly how he succeeded in bringing together the works of his predecessors in Greek philosophy, and how he pursued, either personally or through others, his investigations in the realm of natural phenomena. Pliny claimed that Alexander placed under Aristotle's orders all the hunters, fishermen, and fowlers of the royal kingdom and all the overseers of the royal forests, lakes, ponds and cattle-ranges, and Aristotle's works on zoology make this statement more believable. Aristotle was fully informed about the doctrines of his predecessors, and Strabo asserted that he was the first to accumulate a great library. During the last years of Aristotle's life the relations between him and Alexander became very strained, owing to the disgrace and punishment of Callisthenes, whom Aristotle had recommended to Alexander. Nevertheless, Aristotle continued to be regarded at Athens as a friend of Alexander and a representative of Macedonia. Consequently, when Alexander's death became known in Athens, and the outbreak occurred which led to the Lamian war, Aristotle shared in the general unpopularity of the Macedonians. The charge of impiety, which had been brought against Anaxagoras and Socrates, was now, with even less reason, brought against Aristotle. He left the city, saying (according to many ancient authorities) that he would not give the Athenians a chance to sin a third time against philosophy. He took up residence at his country house at Chalcis, in Euboea, and there he died the following year, 322 BC. His death was due to a disease, reportedly 'of the stomach', from which he had long suffered. The story that his death was due to hemlock poisoning, as well as the legend that he threw himself into the sea "because he could not explain the tides," is without historical foundation. Very little is known about Aristotle's personal appearance except from hostile sources. The statues and busts of Aristotle, possibly from the first years of the Peripatetic School, represent him as sharp and keen of countenance, and somewhat below the average height. His character—as revealed by his writings, his will (which is undoubtedly genuine), fragments of his letters and the allusions of his unprejudiced contemporaries—was that of a high-minded, kind-hearted man, devoted to his family and his friends, kind to his slaves, fair to his enemies and rivals, grateful towards his benefactors. When Platonism ceased to dominate the world of Christian speculation, and the works of Aristotle began to be studied without fear and prejudice, the personality of Aristotle appeared to the Christian writers of the 13th century, as it had to the unprejudiced pagan writers of his own day, as calm, majestic, untroubled by passion, and undimmed by any great moral defects, "the master of those who know". Aristotle's legacy also had a profound influence on Islamic thought and philosophy during the middle ages. The likes of Avicenna, Farabi, and Yaqub ibn Ishaq al-Kindi[http://www.ummah.net/history/scholars/KINDI.html 1] were a few of the major proponents of the Aristotelian school of thought during the Golden Age of Islam.

Methodology

Aristotle defines philosophy in terms of essence, saying that philosophy is "the science of the universal essence of that which is actual". Plato had defined it as the "science of the idea", meaning by idea what we should call the unconditional basis of phenomena. Both pupil and master regard philosophy as concerned with the universal; Aristotle, however, finds the universal in particular things, and called it the essence of things, while Plato finds that the universal exists apart from particular things, and is related to them as their prototype or exemplar. For Aristotle, therefore, philosophic method implies the ascent from the study of particular phenomena to the knowledge of essences, while for Plato philosophic method means the descent from a knowledge of universal ideas to a contemplation of particular imitations of those ideas. In a certain sense, Aristotle's method is both inductive and deductive, while Plato's is essentially deductive. In Aristotle's terminology, the term natural philosophy corresponds to the phenomena of the natural world, which include: motion, light, and the laws of physics. Many centuries later these subjects would later become the basis of modern science, as studied through the scientific method. The term philosophy is distinct from metaphysics, which is what moderns term philosophy. In the larger sense of the word, he makes philosophy coextensive with reasoning, which he also called "science". Note, however, that his use of the term science carries a different meaning than that which is covered by the scientific method. "All science (dianoia) is either practical, poetical or theoretical." By practical science he understands ethics and politics; by poetical, he means the study of poetry and the other fine arts; while by theoretical philosophy he means physics, mathematics, and metaphysics. The last, philosophy in the stricter sense, he defines as "the knowledge of immaterial being," and calls it "first philosophy", "the theologic science" or of "being in the highest degree of abstraction." If logic, or, as Aristotle calls it, Analytic, be regarded as a study preliminary to philosophy, we have as divisions of Aristotelian philosophy (1) Logic; (2) Theoretical Philosophy, including Metaphysics, Physics, Mathematics, (3) Practical Philosophy; and (4) Poetical Philosophy.

Aristotle's epistemology

Logic

History

Aristotle "says that 'on the subject of reasoning' he 'had nothing else on an earlier date to speak about'" (Bocheński, 1951). However, Plato reports that syntax was thought of before him, by Prodikos of Keos, who was concerned by the right use of words. Logic seems to have emerged from dialectics, the earlier philosophers used concepts like reductio ad absurdum as a rule when discussing, but never understood its logical implications. Even Plato had difficulties with logic. Although he had the idea of constructing a system for deduction, he was never able to construct one. Instead, he relied on his dialectic, which was a confusion between different sciences and methods (Bocheński, 1951). Plato thought that deduction would simply follow from premises, so he focused on having good premises so that the conclusion would follow. Later on, Plato realised that a method for obtaining the conclusion would be beneficial. Plato never obtained such a method, but his best attempt was published in his book Sophist, where he introduced his division method (Rose, 1968).

Analytics and the Organon

What we call today Aristotelian logic, Aristotle himself would have labelled analytics. The term logic he reserved to mean dialectics. Most of Aristotle's work is probably not authentic, since it was most likely edited by students and later lecturers. The logical works of Aristotle were compiled into six books at about the time of Christ: #Categories #On Interpretation #Prior Analytics #Posterior Analytics #Topics #On Sophistical Refutations The order of the books (or the teachings from which they are composed) is not certain, but this list was derived from analysis of Aristotle's writings. There is one volume of Aristotle's concerning logic not found in the Organon, namely the fourth book of Metaphysics. (Bocheński, 1951).

Modal logic

Aristotle is also the creator of syllogisms with modalities (modal logic). The word modal refers to the word 'modes', explaining the fact that modal logic deals with the modes of truth. Aristotle introduced the qualification of 'necessary' and 'possible' premises. He constructed a logic which helped in the evaluation of truth but which was very difficult to interpret. (Rose, 1968).

Science

Aristotelian discussions about science had only been qualitative, not quantitative. By the modern definition of the term, Aristotelian philosophy was not science, as this worldview did not attempt to probe how the world actually worked through experiment. For example, in his book The history of animals he claimed that human males have more teeth than females. Had he only made some observations, he would have discovered that this claim is false. Rather, based on what one's senses told one, Aristotelian philosophy then depended upon the assumption that man's mind could elucidate all the laws of the universe, based on simple observation (without experimentation) through reason alone. One of the reasons for this was that Aristotle held that physics was about changing objects with a reality of their own, whereas mathematics was about unchanging objects without a reality of their own. In this philosophy, he could not imagine that there was a relationship between them. In contrast, today's "science" assumes that thinking alone often leads people astray, and therefore one must compare one's ideas to the actual world through experimentation; only then can one see if one's ideas are based in reality. This position is known as empiricism or the scientific method.

Aristotle's metaphysics

Aristotle's four causes

Aristotle names four "causes" of things, but the word cause (Greek: , aitia) is not used in the modern sense of "cause and effect", under which causes are events or states of affairs. Rather, the four causes are like different ways of explaining something: ; The Material Cause (That from which it comes): This is the material that makes up an object, for example, "the bronze and silver ... are causes of the statue and the bowl." ; The Formal Cause (That which it is): This is the blueprint or the idea commonly held of what an object should be. Aristotle says, "The form is the account (and the genera of the account) of the essence (for instance, the cause of an octave is the ratio two to one, and in general number), and the parts that are in the account." ; The Efficient Cause (That which moves it): This is the person who makes an object, or "unmoved movers" (gods) who move nature. For example, "a father is a cause of his child; and in general the producer is a cause of the product and the initiator of the change is a cause." This is closest to the modern definition of "cause". ; The Final Cause (That of which its purpose is): The final cause or telos is the purpose or end that something is supposed to serve. This includes "all the intermediate steps that are for the end ... for example, slimming, purging, drugs, or instruments are for health; all of these are for the end, though they differ in that some are activities while others are instruments." An example of an artifact that has all four causes would be a table, which has material causes (wood and nails), a formal cause (the blueprint, or a generally agreed idea of what tables are), an efficient cause (the carpenter), and a final cause (using it to dine on). Aristotle argues that natural objects such as an "individual man" have all four causes. The material cause of an individual man would be the flesh and bone that make up an individual man. The formal cause would be the blueprint of man, that which is used as a guide to create an individual man and to keep him in a certain state called man. The efficient cause of an individual man would be the father of that man, or in the case of all men an �unmoved mover� who breathed (anima: breath) into the soul (anima: soul) of man. The final cause of man would be as Aristotle stated, �Now we take the human�s function to be a certain kind of life, and take this life to be the soul�s activity and actions that express reason. Hence the excellent man�s function is to do this finely and well. Each function is completed well when its completion expresses the proper virtue. Therefore the human good turns out to be the souls� activity that expresses virtue.�

The difference between natural objects and artifacts

The difference between natural objects and an artifact is that natural objects have self movement. Aristotle defined the difference between a natural object and an artifact when he stated, �In contrast to these, a bed, a cloak, or any other artifact-insofar as it is described as such i.e., as a bed, a cloak, or whatever, and to the extent that it is a product of a craft-has no innate impulse to change; but insofar as it is coincidentally made of stone or earth or a mixture of these, it has an innate impulse to change and just to that extent. This is because a nature is a type of principle and cause of motion and stability within those things to which it primarily belongs in their own right and not coincidentally.� The natural objects are changed to artifacts through crafts but they have an innate impulse of self movement to convert through time to their natural state, and they will all turn into that state when all animals with reason are extinct from the earth.

Modes of causation

Aristotle states two modes of causation:
- Proper Causation: Things take place for the sake of something, and the result is that which is intended.
- Accidental Causation: Things that take place not out of necessity. E.g. things that take place by chance/coincidence. This cause is indeterminable.

Chance

Chance lies in the realm of accidental causes. It is "from what is spontaneous" (but note that what is spontaneous does not come from chance). For a better understanding of Aristotle's conception of "chance" it might be better to think of "coincidence": Something takes place by chance if a person sets out with the intent of having one thing take place, but with the result of another thing (not intended) taking place. For example: A person seeks donations. That person may find another person willing to donate a substantial sum. However, if the person seeking the donations met the person donating, not for the purpose of collecting donations, but for some other purpose, Aristotle would call the collecting of the donation by that particular donator a result of chance. It must be unusual that something happens by chance. In other words, if something happens all or most of the time, we cannot say that it is by chance. However, chance can only apply to human beings. According to Aristotle, chance must involve choice (and thus deliberation), and only humans are capable of deliberation and choice. "What is not capable of action cannot do anything by chance" (Physics, 2.6).

The Five Elements

- Fire which is hot and dry.
- Earth which is cold and dry.
- Air which is hot and wet.
- Water which is cold and wet.
- Aether which is the divine substance that makes up the heavens These four elements interchange (i.e. Fire ↔ Air ↔ Water ↔ Earth etc.), while aether is on its own. The Sun keeps this cycle going. God keeps the Sun going (and thus the Sun is eternal).

Aristotle's ethics

Although Aristotle wrote several works on ethics, the major one was the Nicomachean Ethics, which is considered one of Aristotle's greatest works; it discusses virtues. The ten books which comprise it are based on notes from his lectures at the Lyceum and were either edited by or dedicated to Aristotle's son, Nicomachus. Aristotle believed that ethical knowledge is not certain knowledge (like metaphysics and epistemology) but is general knowledge. Also, as it is not a theoretical discipline, he thought a person had to study in order to become "good." Thus, if a person was to become virtuous, they could not simply study what virtue is, they had to actually do virtuous activity. In order to do this, Aristotle had to first establish what was virtuous. He began by determining that everything was done with some goal in mind and that goal is 'good.' The ultimate goal he called the Highest Good. Aristotle contested that happiness could not be found only in pleasure or only in fame and honor. He finally finds happiness "by ascertaining the specific function of man. But what is this function that will bring happiness? To determine this, Aristotle analyzed the soul and found it to have three parts: the Nutritive Soul (plants, animals and humans), the Perceptive Soul (animals and humans) and the Rational Soul (humans only). Thus, a human's function is to do what makes it human, to be good at what sets it apart from everything else: the ability to reason or Nous. A person that does this is the happiest because they are fulfulling their purpose or nature as found in the rational soul. Depending on how well they did this, Aristotle said people belonged to one of four categories: the Virtuous, the Continent, the Incontinent and the Vicious. Aristotle believes that every ethical virtue is an intermediate condition between excess and deficiency. This does not mean Aristotle believed in moral relativism, however. He set certain emotions (e.g., hate, envy, jealousy, spite, etc.) and certain actions (e.g., adultery, theft, murder, etc.) as being always wrong, regardless of the situation or the circumstances.

Nicomachean ethics

In Nicomachean Ethics, Aristotle focuses on the importance of continually behaving virtuously and developing virtue rather than committing specific good actions. This can be opposed to Kantian ethics, in which the primary focus is on individual action. Nicomachean Ethics emphasizes the importance of context to ethical behaviour — what might be right in one situation might be wrong in another. Aristotle believed that happiness is the end of life and that as long as a person is striving for goodness, good deeds will result from that struggle, making the person virtuous and therefore happy.

Aristotle's critics

goodness (right), a detail of The School of Athens, a fresco by Raphael.]] Aristotle has been criticised on several grounds.
- His analysis of procreation is frequently criticised on the grounds that it presupposes an active, ensouling masculine element bringing life to an inert, passive, lumpen female element; it is on these grounds that some feminist critics refer to Aristotle as a misogynist.
- At times, the objections that Aristotle raises against the arguments of his own teacher, Plato, appear to rely on faulty interpretations of those arguments.
- Although Aristotle advised, against Plato, that knowledge of the world could only be obtained through experience, he frequently failed to take his own advice. Aristotle conducted projects of careful empirical investigation, but often drifted into abstract logical reasoning, with the result that his work was littered with conclusions that were not supported by empirical evidence; for example, his assertion that objects of different mass fall at different speeds under gravity, which was later refuted by John Philoponus. Credit is often given to Galileo, even though Philopinus lived centuries before him.
- In the Middle Ages, roughly from the 12th century to the 15th century, the philosophy of Aristotle became firmly established dogma. Although Aristotle himself was far from dogmatic in his approach to philosophical inquiry, two aspects of his philosophy might have assisted its transformation into dogma. His works were wide-ranging and systematic so that they could give the impression that no significant matter had been left unsettled. He was also much less inclined to employ the sceptical methods of his predecessors, Socrates and Plato.
- Some academics have suggested that Aristotle was unaware of much of the current science of his own time, and that he was a far lesser mathematician than many of his learned contemporaries. Aristotle was called not a great philosopher, but "The Philosopher" by Scholastic thinkers. These thinkers blended Aristotelian philosophy with Christianity, bringing the thought of Ancient Greece into the Middle Ages. It required a repudiation of some Aristotelian principles for the sciences and the arts to free themselves for the discovery of modern scientific laws and empirical methods. The Western mind is "Aristotelian". By this we mean that it formats the external world into factual and "scien"-tific categories. (By "Scien"-tific we mean that something is knowable or known. Latin scientia = knowledge). Under the premise of external categorization, the Aristotelian mind has come to equate "experience" with the unified chronical and spatial ontological structure that is the "external" universe -- visible, audible and sensible by the handful of our common, well-identified senses. By so equating the two, the Aristotelian mind is fully confident, or fully "positive" of the meanings of its utterances and the purposes of all actions. That is to say, it dismisses the possibility of dubious meanings as interpreted by subjects that are at variance in perspectives or phenomenology, and it dismisses the importance of anything other than an objectively defined "purpose" to an action. Therefore, the Aristotelian mind assumes that when subject A utters "I am X," he or she is referring to the same experience and is expressing the same purpose as subject B who also utters "I am X."

Bibliography

Note: Bekker numbers are often used to uniquely identify passages of Aristotle. They are identified below where available.

Major works

The extant works of Aristotle are broken down according to the five categories in the Corpus Aristotelicum. Not all of these works are considered genuine, but differ with respect to their connection to Aristotle, his associates and his views. Some, such as the Athenaion Politeia or the fragments of other politeia are regarded by most scholars as products of Aristotle's "school" and compiled under his direction or supervision. Other works, such On Colours may have been products of Aristotle's successors at the Lyceum, e.g., Theophrastus and Straton. Still others acquired Aristotle's name through similarities in doctrine or content, such as the De Plantis, possibly by Nicolaus of Damascus. A final category, omitted here, includes medieval palmistries, astrological and magical texts whose connection to Aristotle is purely fanciful and self-promotional. Those that are seriously disputed are marked with an asterisk.

Logical writings

- Organon (collected works on logic):
- (1a) Categories (or Categoriae)
- (16a) On Interpretation (or De Interpretatione)
- (24a) Prior Analytics (or Analytica Priora)
- (71a) Posterior Analytics (or Analytica Posteriora)
- (100b) Topics (or Topica)
- (164a) On Sophistical Refutations (or De Sophisticis Elenchis)

Physical and scientific writings

- (184a) Physics (or Physica)
- (268a) On the Heavens (or De Caelo)
- (314a) On Generation and Corruption (or De Generatione et Corruptione)
- (338a) Meteorology (or Meteorologica)
- (391a) On the Cosmos (or De Mundo, or On the Universe)
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- (402a) On the Soul (or De Anima)
- (436a) Little Physical Treatises (or Parva Naturalia):
- On Sense and the Sensible (or De Sensu et Sensibilibus)
- On Memory and Reminiscence (or De Memoria et Reminiscentia)
- On Sleep and Sleeplessness (or De Somno et Vigilia)
- On Dreams (or De Insomniis)
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- On Prophesying by Dreams (or De Divinatione per Somnum)
- On Longevity and Shortness of Life (or De Longitudine et Brevitate Vitae)
- On Youth and Old Age (On Life and Death) (or De Juventute et Senectute, De Vita et Morte)
- On Breathing (or De Respiratione)
- (481a) On Breath (or De Spiritu)
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- (486a) History of Animals (or Historia Animalium, or On the History of Animals, or Description of Animals)
- (639a) On the Parts of Animals (or De Partibus Animalium)
- (698a) On the Gait of Animals (or De Motu Animalium, or On the Movement of Animals)
- (704a) On the Progression of Animals (or De Incessu Animalium)
- (715a) On the Generation of Animals (or De Generatione Animalium)
- (791a) On Colours (or De Coloribus)
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- (800a) De audibilibus
- (805a) Physiognomics (or Physiognomonica)
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- On Plants (or De Plantis)
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- (830a) On Marvellous Things Heard (or Mirabilibus Auscultationibus, or On Things Heard)
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- (847a) Mechanical Problems (or Mechanica)
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- (859a) Problems (or Problemata)
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- (968a) On Indivisible Lines (or De Lineis Insecabilibus)
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- (973a) Situations and Names of Winds (or Ventorum Situs)
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Metaphysical writings

- (980a) Metaphysics (or Metaphysica)

Ethical writings

- (1094a) Nicomachean Ethics (or Ethica Nicomachea, or The Ethics)
- (1181a) Great Ethics (or Magna Moralia)
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- (1214a) Eudemian Ethics (or Ethica Eudemia)
- (1249a) Virtues and Vices (or De Virtutibus et Vitiis Libellus, Libellus de virtutibus)
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- (1252a) Politics (or Politica)
- (1343a) Economics (or Oeconomica)

Aesthetic writings

- (1354a) Rhetoric (or Ars Rhetorica, or The Art of Rhetoric or Treatise on Rhetoric)
- Rhetoric to Alexander (or Rhetorica ad Alexandrum)
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- (1447a) Poetics (or Ars Poetica)

Writings absent from Corpus Aristotelicum

- The Constitution of the Athenians (or Athenaion Politeia, or The Athenian Consitution)
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- On Melissus, On Xenophanes, and On Gorgias. These are sometimes grouped together and called the "MXG" writings. They clearly are not written by Aristotle, and are believed to date from the fifth century AD. However, because they have frequently been attributed to him in the past, they are often included in compilations of his writings (for example, in the Loeb Classical Library).

Specific editions

- Princeton University Press: The Complete Works of Aristotle: The Revised Oxford Translation (2 Volume Set; Bollingen Series, Vol. LXXI, No. 2), edited by Jonathan Barnes ISBN 0-691-09950-2 (The most complete recent translation of Aristotle's extant works)
- Oxford University Press: Clarendon Aristotle Series. [http://www.oup.com/us/catalog/general/series/ClarendonAristotleSeries/?view=usa Scholarly edition]
- Harvard University Press: Loeb Classical Library (hardbound; publishes in Greek, with English translations on facing pages)

Named after Aristotle

- Aristoteles crater on the Moon.
- The Aristotle University of Thessaloniki
- Aristotle's Cockney legacy - The name of Aristotle, like that of J. Arthur Rank, became a common expression in Cockney rhyming slang.

References

Needless to say, the secondary literature on Aristotle is vast. The following references are only a small selection.
- A popular exposition for the general reader.
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- A detailed and scholarly work, but very readable.
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- For the general reader.

External links

Aristotle Aristotle
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- [http://Aristotle.thefreelibrary.com/ A brief biography and e-texts presented one chapter at a time]
- [http://www.utm.edu/research/iep/a/aristotl.htm The Internet Encyclopedia of Philosophy: Aristotle.], 2004.
- [http://www.non-contradiction.com/ An extensive collection of Aristotle's philosophy and works, including lesser known texts]
- [http://www.virtuescience.com/nicomachean-ethics.html Nicomachean Ethics by Aristotle.]
- [http://uk.arxiv.org/abs/physics/0505172 Aristotle and Indian logic]
- O'Connor, J. John & Robertson, Edmund F., [http://www-history.mcs.st-andrews.ac.uk/Mathematicians/Aristotle.html Aristotle], 2004.
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- [http://www.greektexts.com/library/Aristotle/index.html Large collection of Aristotle's texts, presented page by page]
- [http://www.greek-literature-online.com/aristotle/ Read Aristotle's works online]
- [http://www.newadvent.org/cathen/01713a.htm Source of most of the Biography and Methodology sections, as well as more overview]
- Category:Aristotle Category:Ancient Greek philosophers Category:Aristotelian philosophers Category:Ancient Greek mathematicians Category:Empiricists Category:Rhetoric Category:Greek logicians Category:Meteorologists ko:아리스토텔레스 ms:Aristotle ja:アリストテレス simple:Aristotle th:อริสโตเติล

Anatomy

Anatomy (from the Greek anatomia, from anatemnein, to cut up, cut open), is the branch of biology that deals with the structure and organization of living things. It can be divided into animal anatomy (zootomy) and plant anatomy (phytonomy). Major branches of anatomy include comparative anatomy, histology, and human anatomy. Animal anatomy may include the study of the structure of different animals, when it is called comparative anatomy or animal morphology, or it may be limited to one animal only, in which case it is spoken of as special anatomy. From a utilitarian point of view the study of humans is the most important division of special anatomy, and this human anatomy may be approached from different points of view. From that of Medicine it consists of a knowledge of the exact form, position, size and relationship of the various structures of the healthy human body, and to this study the term descriptive or topographical human anatomy is given, though it is often, less happily, spoken of as anthropotomy. So intricate is the human body that only a small number of professional human anatomists, after years of patient observation, are complete masters of all its details; most of them specialize on certain parts, such as the brain or viscera, contenting themselves with a good working knowledge of the rest. Topographical anatomy must be learned by repeated dissection and inspection of dead human bodies. It is no more a science than a pilot's knowledge is, and, like that knowledge, must be exact and available in moments of emergency. From the morphological point of view, however, human anatomy is a scientific and fascinating study, having for its object the discovery of the causes which have brought about the existing structure of humans, and needing a knowledge of the allied sciences of embryology or developmental biology, phylogeny, and histology. Pathological anatomy (or morbid anatomy) is the study of diseased organs, while sections of normal anatomy, applied to various purposes, receive special names such as medical, surgical, gynaecological, artistic and superficial anatomy. The comparison of the anatomy of different races of humans is part of the science of physical anthropology or anthropological anatomy. In the present edition of this work the subject of anatomy is treated systematically rather than topographically. Each anatomical article contains first a description of the structures of an organ or system (such as nerves, arteries, heart, and so forth), as it is found in humans; this is followed by an account of the development (embryology) and comparative anatomy (morphology), as far as vertebrate animals are concerned; but only those parts of the lower animals which are of interest in explaining human body structure are here dealt with. The articles have a twofold purpose; first, to give enough details of structure to make the articles on physiology, surgery, medicine and pathology intelligible; and, secondly, to give the non-expert inquirer, or the worker in some other branch of science, the chief theories on which the modern scientific groundwork of anatomy is built.
- Major body systems:
- Integumentary system
- Muscular system
- Nervous system
- Reproductive system
- Respiratory system
- Excretory system
- Circulatory system
- Lymphatic system
- Skeletal system (Human skeleton)
- Endocrine system
- Digestive system
- Immune system
- Organs:
- Anus
- Appendix
- Brain
- Breast
- Colon or large intestine
- Diaphragm
- Ear
- Eye
- Heart
- Kidney
- Labia
- Larynx
- Liver
- Lung
- Nose
- Ovary
- Pharynx
- Pancreas
- Penis
- Placenta
- Rectum
- Skin
- Small intestine
- Spleen
- Stomach
- Tongue
- Uterus
- Bones in the human skeleton:
- Collar bone (clavicle)
- Thigh bone (femur)
- Humerus
- Mandible
- Patella
- Radius
- Skull
- Tibia
- Ulna
- Rib
- Vertebrae
- Pelvis
- Sternum
- Glands:
- Ductless gland
- Mammary gland
- Salivary gland
- Thyroid gland
- Parathyroid gland
- Adrenal gland
- Pituitary gland
- Pineal gland
- Tissues:
- Connective tissue
- Endothelial tissue
- Epithelial tissue
- Glandular tissue
- Lymphoid tissue
- Externally visible parts of the human body:
- Abdomen
- Arm
- Back
- Buttock
- Chest
- Ear
- Eye
- Face
- Genitals
- Head
- Joint
- Leg
- Mouth
- Neck
- Scalp
- Skin
- Teeth
- Tongue
- Other anatomic terms (not classified):
- Artery
- Coelom
- Diaphragm
- Gastrointestinal tract
- Hair
- Exoskeleton
- Lip
- Nerve
- Peritoneum
- Serous membrane
- Skeleton
- Skull
- Spinal cord
- Vein

External links

- [http://brainmaps.org High-Resolution Cytoarchitectural Primate Brain Atlases]
- [http://www.innerbody.com/htm/body.html Free online anatomy atlas]
- [http://www.npac.syr.edu/projects/vishuman/VisibleHuman.html The NPAC Visible Human Viewer]
- [http://cancerweb.ncl.ac.uk/omd/index.html On-Line Medical Dictionary]
- [http://www.bartleby.com/107/ Anatomy of the Human Body by Henry Gray]
- [http://www.rtstudents.com/ Online Radiology Anatomy Resources]
- [http://www.wikimd.org/index.php?title=Gray%27s_Anatomy Gray's Anatomy wiki]
- http://immunity-info.net Category:Anatomy ko:해부학 ja:解剖学 simple:Anatomy th:กายวิภาคศาสตร์

Physiology

Physiology (in Greek physis = nature and logos = word) is the study of the mechanical, physical, and biochemical functions of living organisms. Physiology has traditionally been divided into plant physiology and animal physiology but the principles of physiology are universal, no matter what particular organism is being studied. For example, what is learned about the physiology of yeast cells can also apply to human cells. The field of animal physiology extends the tools and methods of human physiology to non-human animal species. Plant physiology also borrows techniques from both fields. Its scope of subjects is at least as diverse as the tree of life itself. Due to this diversity of subjects, research in animal physiology tends to concentrate on understanding how physiological traits changed throughout the evolutionary history of animals. Other major branches of scientific study that have grown out of physiology research include biochemistry, biophysics, biomechanics, and pharmacology.

History

It was Abu Bakr Al Razi (popularly known as Rhazes) who described certain physiological parameters when he went to establish a hospital at Baghdad in the eighth century AD. Razi was followed by Al Kindi, who wrote a treatise on human physiology. Anatomist William Harvey described blood circulation in the 17th century, providing the beginning of experimental physiology. Herman Boerhaave is sometimes referred to as the father of physiology due to his exemplary teaching in Leiden and textbook 'Institutiones medicae'(1708).

Areas of physiology

Human and animal

Human physiology (main article) is the most complex area in physiology. This area has several subdivisions which overlap with each other. Many animals have similar anatomy to humans and so share many of these areas.
- myophysiology deals with the operation of muscles
- neurophysiology concerns the physiology of brains and nerves
- cell physiology addresses the functioning of individual cells
- membrane physiology focuses on the exchange of molecules across the cell membrane
- respiratory physiology goes into the mechanics of gaseous exchange at the lung
- circulation also known as cardiovascular physiology, deals with the heart, blood and blood vessels and issues arising
- renal physiology focuses on the excretion of ions and other metabolites at the kidney
- endocrinology covers endocrine hormones which affect every cell in the body
- neuroendocrinology concerns the complex interactions of the neurological and endocrinological systems which together regulate physiology
- reproductive physiology concerns the reproductive cycle

Plant

Plant physiology has differing subdivisions. For example, since plants do not have muscles and nerves, neither myophysiology nor neurophysiology applies.
- Transpiration is the study of water loss from the plant leaves
- Photosynthesis is the conversion of sunlight energy, water and CO₂ to form sugars (glucose). Category : Subjects Taught in Medical School ja:生理学 simple:Physiology th:สรีรวิทยา

Theophrastus

Theophrastus, a native of Eresus in Lesbos born c. 372 BC, was the successor of Aristotle in the Peripatetic school. His given name was Tyrtamus, but he later became known by the nickname "Theophrastus", given to him, it is said, by Aristotle to indicate the grace of his conversation. He released the first recorded message in a bottle in order to show that the Mediterranean Sea was formed by the inflowing Atlantic Ocean. After receiving his first introduction to philosophy in Lesbos from one Leucippus or Alcippus, he proceeded to Athens, and became a member of the Platonic circle. After Plato's death he attached himself to Aristotle, and in all probability accompanied him to Stagira. The intimate friendship of Theophrastus with Callisthenes, the fellow-pupil of Alexander the Great, the mention made in his will of an estate belonging to him at Stagira, and the repeated notices of the town and its museum in the History of Plants, are facts which point to this conclusion. Aristotle in his will made him guardian of his children, bequeathed to him his library and the originals of his works, and designated him as his successor at the Lyceum on his own removal to Chalcis. Eudemus of Rhodes also had some claims to this position, and Aristoxenus is said to have resented Aristotle's choice. Theophrastus presided over the Peripatetic school for thirty-five years, and died in 287 BC. Under his guidance the school flourished greatly — there were at one period more than 2000 students — and at his death he bequeathed to it his garden with house and colonnades as a permanent seat of instruction. Menander was among his pupils. His popularity was shown in the regard paid to him by Philip, Cassander and Ptolemy, and by the complete failure of a charge of impiety brought against him. He was honoured with a public funeral, and "the whole population of Athens, honouring him greatly, followed him to the grave" (Diog. Laërt.). From the lists of the ancients it appears that the activity of Theophrastus extended over the whole field of contemporary knowledge. His writing probably differed little from the Aristotelian treatment of the same themes, though supplementary in details. He served his age mainly as a great popularizer of science. The most important of his books are two large botanical treatises, On the History of Plants, in nine books (originally ten), and On the Causes of Plants, in six books (originally eight), which constitute the most important contribution to botanical science during antiquity and the middle ages. We also possess in fragments a History of Physics, a treatise On Stones, and a work On Sensation, and certain metaphysical Airoptai, which probably once formed part of a systematic treatise. He made the first known reference to the phenomenon of pyroelectricity, noting in 314 BC that the mineral tourmaline becomes charged when heated. Various smaller scientific fragments have been collected in the editions of JG Schneider (1818–21) and F Wimmer (1842–62) and in Usener's Analecta Theophrastea. The Ethical Characters deserves a separate mention. The work consists of brief, vigorous and trenchant delineations of moral types, which contain a most valuable picture of the life of his time. They form the first recorded attempt at systematic character writing. The book has been regarded by some as an independent work; others incline to the view that the sketches were written from time to time by Theophrastus, and collected and edited after his death; others, again, regard the Characters as part of a larger systematic work, but the style of the book is against this. Theophrastus has found many imitators in this kind of writing, notably Hall (1608), Sir Thomas Overbury (1614–16), Bishop Earle (1628) and Jean de La Bruyère (1688), who also translated the Characters.

References

- Category:Ancient Greek botanists Category:Ancient Greek philosophers

Herophilos

Herophilos, sometimes Latinized Herophilus (335-280 BC), was a Greek physician. He was born in Chalcedon in Asia Minor (now Kadiköy, Turkey). He is known as the first anatomist in history. Together with Erasistratus he is regarded as a founder of the great medical school of Alexandria. He was the first to base his conclusions on dissection of the human body. He studied the brain, recognizing it as the center of the nervous system and the site of intelligence. He also paid particular attention to the nervous system, distinguishing nerves from blood vessels and the motor from the sensory nerves. Other areas of his anatomical study include the eye, liver, pancreas, and the alimentary tract, as well as the salivary and genital organs. His works were lost but were much quoted by Galen in the 2nd century AD. Another figure by this name (Herophilus) was an imposter in the time of Julius Caesar who pretended to be the grandson of Marius. Caesar banished him for sedition, and he was later strangled in prison. Category:History of ancient medicine Category:History of neuroscience Category:Anatomists Category:335 BC births Category:280 BC deaths Category:Anatomists

Pliny the Elder

Gaius Plinius Secundus, (23–79) better known as Pliny the Elder, was an ancient author and Natural philosopher of some importance who wrote Naturalis Historia. He was the son of a Roman eques by the daughter of the Senator Gaius Caecilius of Novum Comum. He was born at Como, not (as is sometimes supposed) at Verona: it is only as a native of Gallia Transpadana that he calls Catullus of Verona his conterraneus, or fellow-countryman, not his municeps, or fellow-townsman [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/praefatio
- .html#1 (Praef. §1)].

Chronology

Before 35 [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/37
- .html#81 (N.H. xxxvii.81)] his father took him to Rome, where he was educated under his father's friend, the poet and military commander, P. Pomponius Secundus, who inspired him with a lifelong love of learning. Two centuries after the death of the Gracchi, Pliny saw some of their autograph writings in his preceptor's library [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/13
- .html#83 (xiii.83)], and he afterwards wrote that preceptor's Life. He mentions the grammarians and rhetoricians, Remmius Palaemon and Arellius Fuscus ([http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/14
- .html#4 xiv.4]; [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/33
- .html#152 xxxiii.152]), and he may have been their student. In Rome he studied botany in the topiarius (garden) of the aged Antonius Castor [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/25
- .html#9 (xxv.9)], and saw the fine old lotus-trees in the grounds that had once belonged to Crassus [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/17
- .html#5 (xvii.5)]. He also viewed the vast structure raised by Caligula [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/36
- .html#111 (xxxvi.111)], and probably witnessed the triumph of Claudius over Britain in 44 [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/3
- .html#119 (iii.119)]. Under the influence of Seneca the Younger he became a keen student of philosophy and rhetoric, and began practicing as an advocate. He saw military service under Corbulo in Germania Inferior in 47, taking part in the Roman conquest of the Chauci and the construction of the canal between the rivers Maas and Rhine (xvi. [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/16
- .html#2 2] and [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/16
- .html#5 5]). As a young commander of cavalry (praefectus alae) he wrote in his winter-quarters a work on the use of missiles on horseback (De jaculatione equestri), with some account of the points of a good horse [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/8
- .html#162 (viii.162)]. In Gaul and Spain he learnt the meanings of a number of Celtic words [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/30
- .html#40 (xxx.40)]. He took note of sites associated with the Roman invasion of Germany, and, amid the scenes of the victories of Drusus, he had a dream in which the victor enjoined him to transmit his exploits to posterity (Plin. Epp. iii.5, 4). The dream prompted Pliny to begin forthwith a history of all the wars between the Romans and the Germans. He probably accompanied his father's friend Pomponius on an expedition against the Chatti (50), and visited Germany for a third time (50s) as a comrade of the future emperor, Titus Flavius [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/praefatio
- .html#3 (Praef. §3)]. Under Nero he lived mainly in Rome. He mentions the map of Armenia and the neighbourhood of the Caspian Sea, which was sent to Rome by the staff of Corbulo in 58 [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/6
- .html#40 (vi.40)]. He also saw the building of Nero's "golden house" after the fire of 64 [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/36
- .html#111 (xxxvi.111)]. Meanwhile he was completing the twenty books of his History of the German Wars, the only authority expressly quoted in the first six books of the Annals of Tacitus (1.69), and probably one of the principal authorities for the Germania. It was superseded by the writings of Tacitus, and, early in the 5th century, Symmachus had little hope of finding a copy (Epp. xiv.8). He also devoted much of his time to writing on the comparatively safe subjects of grammar and rhetoric. A detailed work on rhetoric, entitled Studiosus, was followed by eight books, Dubii sermonis, in 67. Under his friend Vespasian he returned to the service of the state, serving as procurator in Gallia Narbonensis (70) and Hispania Tarraconensis (73), and also visiting the province of Gallia Belgica (74). During his stay in Spain he became familiar with the agriculture and the mines of the country, besides paying a visit to Africa [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/7
- .html#37 (vii.37)]. On his return to Italy he accepted office under Vespasian, whom he used to visit before daybreak for instructions before proceeding to his official duties, after the discharge of which he devoted all the rest of his time to study (Plin. Epp. iii.5, 9). He completed a History of his Times in thirty-one books, possibly extending from the reign of Nero to that of Vespasian, and deliberately reserved it for publication after his death [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/praefatio
- .html#20 (N. H., Praef. 20)]. It is quoted by Tacitus (Ann. xiii.20, xv.53; Hist. iii.29), and is one of the authorities followed by Suetonius and Plutarch. He also virtually completed his great work, the Naturalis Historia, an encyclopedia into which Pliny collected much of the knowledge of his time. The work had been planned under the rule of Nero. The materials collected for this purpose filled rather less than 160 volumes in 23, when Larcius Licinus, the praetorian legate of Hispania Tarraconensis, vainly offered to purchase them for a sum equivalent to more than £3,200 (1911 estimated value) or £200,000 (2002 estimated value). He dedicated the work to Titus Flavius in 77.

Vesuvius

Soon afterwards he received from Vespasian the appointment of praefect of the Roman fleet at Misenum. On August 24, 79 he was stationed at Misenum, at the time of the great eruption of Mount Vesuvius, which overwhelmed Pompeii and Herculaneum. A desire to observe the phenomenon directly, and also to rescue some of his friends from their perilous position on the shore of the Bay of Naples, led to his launching his galleys and crossing the bay to Stabiae (Castellammare di Stabia). Although he believed that Stabiae would be a safe distance from the eruption, he did not take into account the possibility of the volcano releasing toxic gases; consequently, he was asphyxiated. He is still remembered in vulcanology where the term plinian (or plinean) refers to a very violent eruption of a volcano after a long period of being dormant. The term ultra-plinian is reserved for the most violent type of plinian eruption such as the 1883 destruction of Krakatoa. The story of his last hours is told in an [http://www.gutenberg.org/etext/2811 interesting letter] addressed twenty-seven years afterwards to Tacitus by the Elder Pliny's nephew and heir, Pliny the Younger (Epp. vi.16), who also sends to another correspondent an account of his uncle's writings and his manner of life (iii.5):

"He began to work long before daybreak.…He read nothing without making extracts; he used even to say that there was no book so bad as not to contain something of value. In the country it was only the time when he was actually in his bath that was exempted from study. When travelling, as though freed from every other care, he devoted himself to study alone. In short, he deemed all time wasted that was not employed in study."

His only writings to have survived to modern times is the Naturalis historia. It was used as an authority over the following centuries by countless scholars.

Philosophy

Like many of the finest spirits under the early Empire, Pliny was an adherent to the Stoics. He was acquainted with their noblest representative, Thrasea Paetus, and he also came under the influence of Seneca. The Stoics were given to the study of nature, while their moral teaching was agreeable to one who, in his literary work, was unselfishly eager to benefit and to instruct his contemporaries ([http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/praefatio
- .html#16 Praef. 16], [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/28
- .html#2 xxviii.2], [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/29
- .html#1 xxix.1]). He was also influenced by the Epicurean and the Academic and the revived Pythagorean schools. But his view of nature and of God is essentially Stoic. It was only (he declares) the weakness of humanity that had embodied the Being of God in many human forms imbued with human faults and vices [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/2
- .html#148 (ii.148)]. The Godhead was really one; it was the soul of the eternal world, displaying its beneficence on the earth, as well as in the sun and stars (ii.[http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/2
- .html#12 12 seq.], [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/2
- .html#154 154 seq.). The existence of a divine Providence was uncertain [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/2
- .html#19 (ii.19)], but the belief in its existence and in the punishment of wrong-doing was salutary [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/2
- .html#26 (ii.26)]; and the reward of virtue consisted in the elevation to Godhead of those who resembled God in doing good to man ([http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/2
- .html#18 ii.18], Deus est mortali juvare mortalem, et haec ad aeternam gloriam via). It was wrong to inquire into the future and do violence to nature by resorting to magical arts ([http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/2
- .html#114 ii.114], [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/30
- .html#3 xxx.3]); but the significance of prodigies and portents is not denied (ii.[http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/2
- .html#92 92], [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/2
- .html#199 199], [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/2
- .html#232 232]). Pliny's view of life is gloomy; he regards the human race as plunged in ruin and in misery ([http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/2
- .html#24 ii.24], [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/7
- .html#130 vii.130]). Against luxury and moral corruption he indulges in declamations, which are so frequent that (like those of Seneca) they at last pall upon the reader; and his rhetorical flourishes against practically useful inventions (such as the art of navigation) are wanting in good sense and good taste [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/19
- .html#6 (xix.6)]. With the proud national spirit of a Roman he combines an admiration of the virtues by which the Republic had attained its greatness ([http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/16
- .html#14 xvi.14], [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/27
- .html#3 xxvii.3], [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/37
- .html#201 xxxvii.201]). He does not suppress historical facts unfavourable to Rome (xxxiv.139), and while he honours eminent members of distinguished Roman houses, he is free from Livy's undue partiality for the aristocracy. The agricultural classes and the old landlords of the equestrian order (Cincinnatus, Curius Dentatus, Serranus and the Elder Cato) are to him the pillars of the state; and he bitterly laments the decline of agriculture in Italy (xviii.[http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/18
- .html#21 21] and [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/18
- .html#35 35], latifundia perdidere Italiam). Accordingly, for the early history of Rome, he prefers following the pre-Augustan writers; but he regards the imperial power as indispensable for the government of the Empire, and he hails the salutaris exortus Vespasiani [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/33
- .html#51 (xxxiii.51)].

Literature

At the conclusion of his literary labours, as the only Roman who had ever taken for his theme the whole realm of nature, he prays for the blessing of the universal mother on his completed work. In literature he assigns the highest place to Homer and to Cicero [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/17
- .html#37 (xvii.37 seq.)]; and the next to Virgil. He was influenced by the works of the Numidian king Juba II, who he called "my Master". He takes a keen interest in nature, and in the natural sciences, studying them in a way that was then new in Rome, while the small esteem in which studies of this kind were held does not deter him from endeavouring to be of service to his fellow countrymen [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/22
- .html#15 (xxii.15)]. The scheme of his great work is vast and comprehensive, being nothing short of an encyclopedia of learning and of art so far as they are connected with nature or draw their materials from it. With a view to this work he studied the original authorities on each subject and was most assiduous in making excerpts from their pages. His indices auctorum are, in some cases, the authorities which he has actually consulted (though in this respect they are not exhaustive); in other cases, they represent the principal writers on the subject, whose names are borrowed second-hand for his immediate authorities. He frankly acknowledges his obligations to all his predecessors in a phrase that deserves to be proverbial ([http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/praefatio
- .html#21 Praef. 21], plenum ingenni pudoris fateri per quos profeceris). He had neither the temperament for original investigation, nor the leisure necessary for the purpose. It is obvious that one who spent all his time in reading and in writing, and in making excerpts from his predecessors, had none left for mature and independent thought, or for patient experimental observation of the phenomena of nature. But it must not be forgotten that it was his scientific curiosity as to the phenomena of the eruption of Vesuvius that brought his life of unwearied study to a premature end; and any criticism of his faults of omission is disarmed by the candour of the confession in his preface: nec dubitamus multa esse quae et nos praeterierint; homines enim sumus et occupati officiis. His style betrays the unhealthy influence of Seneca. It aims less at clearness and vividness than at epigrammatic point. It abounds not only in antitheses, but also in questions and exclamations, tropes and metaphors, and other mannerisms of the Silver Age. The rhythmical and artistic form of the sentence is sacrificed to a passion for emphasis that delights in deferring the point to the close of the period. The structure of the sentence is also apt to be loose and straggling. There is an excessive use of the ablative absolute, and ablative phrases are often appended in a kind of vague "apposition" to express the author's own opinion of an immediately previous statement, e.g. [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/35
- .html#80 xxxv.80], dixit (Apelles) ... uno se praestare, quod manum de tabula sciret tollere, memorabili praecepto nocere saepe nimiam diligentiam. About the middle of the 3rd century an abstract of the geographical portions of Pliny's work was produced by Solinus; and early in the 4th century the medical passages were collected in the Medicina Plinii. Early in the 8th century we find Bede in possession of an excellent manuscript of the whole work. In the 9th century Alcuin sends to Charlemagne for a copy of the earlier books (Epp. 103, Jaffé); and Dicuil gathers extracts from the pages of Pliny for his own Mensura orbis terrae (ca. 825). Pliny's work was held in high esteem in the Middle Ages. The number of extant manuscripts is about 200; but the best of the more ancient manuscripts, that at Bamberg, contains only books xxxii-xxxvii. Robert of Cricklade, prior of St. Frideswide at Oxford, dedicated to Henry II a Defloratio consisting of nine books of selections taken from one of the manuscripts of this class, which has been recently recognized as sometimes supplying us with the only evidence for the true text. Among the later manuscripts, the codex Vesontinus, formerly at Besançon (11th century), has been divided into three portions, now in Rome, Paris, and Leiden respectively, while there is also a transcript of the whole of this manuscript at Leiden. A special interest attaches to his account of the manufacture of the papyrus [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/13
- .html#68 (xiii.68 seq.)], and of the different kinds of purple dye [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/9
- .html#130 (ix.130)], while his description of the notes of the nightingale is an elaborate example of his occasional felicity of phrase [http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Pliny_the_Elder/29
- .html#81 (xxix.81 seq.)].

Research after 1500

Sir Thomas Browne expressed a wholesome skepticism about Pliny's dependability in his Pseudodoxia Epidemica (1646): :"Now what is very strange, there is scarce a popular error passant in our days, which is not either directly expressed, or diductively contained in this Work; which being in the hands of most men, hath proved a powerful occasion of their propagation. Wherein notwithstanding the credulity of the Reader is more condemnable then the curiosity of the Author: for commonly he nameth the Authors from whom he received those accounts, and writes but as he reads, as in his Preface to Vespasian he acknowledgeth." [http://penelope.uchicago.edu/pseudodoxia/pseudo18.html#b15] Most of the recent research on Pliny has been concentrated on the investigation of his authorities, especially those which he followed in his chapters on the history of art - the only ancient account of that subject which has survived. A carnelian inscribed with the letters C. PLIN. has been reproduced by Cades (v.211) from the original in the Vannutelli collection. It represents an ancient Roman with an almost completely bald forehead and a double chin; and is almost certainly a portrait, not of Pliny the Elder, but of Pompey the Great. Seated statues of both the Plinies, clad in the garb of scholars of the year 1500, may be seen in the niches on either side of the main entrance to the cathedral church of Como. The elder Pliny's anecdotes of Greek artists supplied Vasari with the subjects of the frescoes which still adorn the interior of his former home at Arezzo.

External links

- [http://www.classics.cam.ac.uk/Everyone/Pompeii/Destruction.html Contemporaneous account of Pliny's death] (the famous letter by Pliny's nephew, Pliny the Younger, in Latin and English)
- [http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Pliny_the_Elder/home.html A complete Latin transcription of the Naturalis Historia] and a [http://www.perseus.tufts.edu/cgi-bin/ptext?lookup=Plin.+Nat.+toc Complete 1855 English translation]
- [http://www.livius.org/pi-pm/pliny/pliny_e.html Pliny the Elder] Biography and summary of Natural History
- Robert Harris's Pompeii: A Novel contains an accurate, if fictionalized portrait of Pliny the Elder and his last hours.

References

- Category:23 births Category:79 deaths Category:Ancient Romans Category:Pre-Linnaean botanists Category:Roman era philosophers Category:Roman era writers

Galen

Claudius Galenus of Pergamum (131-201 AD), better known as Galen, was an ancient Greek physician. His views dominated European medicine for over a thousand years.

Life

Galen was born in Pergamum (modern-day Bergama, Turkey), the son of Nicon, a wealthy architect. His interests were eclectic - agriculture, architecture, astronomy, astrology, philosophy - until he concentrated on medicine. By the age of twenty he had become a therapeutes ("attendant" or "associate") of the god Asclepius in the local temple for four years. After his father's death in 148 or 149 he left to study abroad. He studied in Smyrna and Corinth and at Alexandria. He studied medicine for a total of twelve years. When he returned to Pergamum in 157, he worked as a physician in a gladiator school for three or four years. During this time he gained experience of trauma and wound treatment. He later regarded wounds as "windows into the body". From 162 he lived in Rome where he wrote extensively, lectured and publicly demonstrated his knowledge of anatomy. He gained a reputation as an experienced physician and his practice had widespread clientele. One of them was the consul Flavius Boethius who introduced him to the court where he became a court physician to Emperor Marcus Aurelius. Later he also treated Lucius Verus, Commodus and Septimius Severus. Reputedly he spoke mostly Greek, which was a more respected language of medicine than Latin at the time. He briefly returned to Pergamum during 166-169. Galen spent the rest of his life in the Imperial court, writing and experimenting. He performed vivisections of numerous animals to study the function of the kidneys and the spinal cord. His favorite subject was the barbary ape. Reportedly he employed twenty scribes to write down his words. In 191, fire in the Temple of Peace destroyed some of his records. His exact date of death has traditionally been placed around the year 200, based on a reference from the 10th century Suda Lexicon. Some, however, have argued for dates as late as 216.

Work and impact

Galen transmitted Hippocratic medicine all the way to the Renaissance. His On the Elements According to Hippocrates describes the philosopher's system of four bodily humours, which were identified with the four classical elements. He created his own theories from those principles. In turn, he mainly ignored Latin writings of Celsus. Amongst Galen's own major works is a seventeen-volume On the Usefulness of the Parts of the Human Body. He also wrote about philosophy and philology. His collected works total twenty-two volumes. Galen's own theories, in accord with Plato's, emphasized purposeful creation by a single Creator ("Nature" - Greek phusis) - a major reason why later Christian and Muslim scholars could accept his views. His fundamental principle of life was pneuma (air, breath) that later writers connected with the soul. Pneuma physicon (animal spirit) in the brain took care of movement, perception, and senses. Pneuma zoticon (vital spirit) in the heart controlled blood and body temperature. "Natural spirit" in the liver handled nutrition and metabolism. Galen expanded his knowledge partly by experimenting with live animals. One of his methods was to publicly dissect a living pig and cut its nerve bundles one at a time. Eventually he cut a laryngeal nerve (now also known as Galen's Nerve) and the pig stopped squealing. He tied the ureters of living animals to show that urine comes from the kidneys. He severed spinal cords to demonstrate paralysis. From the modern viewpoint, Galen's theories were partially correct, partially flawed. He demonstrated that arteries carry blood, not air and made first studies about nerve functions, and the brain and heart. He also argued that the mind was in the brain, not in the heart as Aristotle had claimed. However, much of Galen's understanding is flawed from the modern point of view. He did not recognize blood circulation and thought that venous and arterial systems were separate. This view did not change until William Harvey's work in the 17th century. Since most of his knowledge of anatomy was based on dissection of pigs, dogs, and Barbary apes, he also assumed that rete mirabile, a blood vessel plexus of ungulates, also existed in the human body. He also resisted the idea of tourniquets to stop bleeding and vigorously propagated blood letting as a treatment. Galen's authority dominated medicine all the way to the 16th century. Experimenters' disciples did not bother to experiment and studies of physiology and anatomy stopped - Galen had already written about everything. Blood letting became a standard medical procedure. Vesalius presented the first serious challenge to his hegemony. Most of Galen's Greek writings were first translated to the Syriac language by Nestorian monks in the university of Jundi Shapur, Persia. Then Muslim scholars translated them to Arabic, alongside many other Greek classics. They became one of the main sources for Persian scholars such as Avicenna and Rhazes.

External links

- [http://www.med.virginia.edu/hs-library/historical/antiqua/galen.htm Galen]
- [http://www.udayton.edu/~hume/Galen/galen.htm Galen, university dayton]
- [http://www.medicinaantiqua.org.uk/bio_gal.html Galen: A Biographical Sketch]
- [http://www.ancientlibrary.com/medicine/index.html Greek Biology and Medicine] by Henry Osborn Taylor (1922), scanned edition. Chapter 5 is devoted to [http://www.ancientlibrary.com/medicine/0109.html "The Final System: Galen"].
- [http://pacs.unica.it/biblio/lesson2.htm Galen and the Greek-Helenic history of medicine]

Books

- Jeanne Bendick - Galen and the Gateway to Medicine Category:History of ancient medicine Category:Roman era writers Category:Anatomists

1628

Events

- March 1 - writs were issued in February 1628 by Charles I of England that every county in England (not just seaport towns) pay ship tax by this date.
- August 10 - The Swedish 64 gun sailing ship Vasa sinks on her maiden voyage in the Stockholm harbor
- September 6 - Puritans settle Salem which will later become part of Massachusetts Bay Colony.
- October 28 – Siege of La Rochelle ends with the surrender of the Huguenots.
- Charles I reconvenes the English Parliament and accepts the Petition of Right as a concession to gain his subsidies.
- Island of Santorini explodes.
- John Felton assassinates George Villiers, duke of Buckingham.
- William Harvey publishes his findings about blood circulation.

Births

- January 8 - François Henri de Montmorency-Bouteville, duc de Luxembourg, French general (d. 1695)
- January 10 - George Villiers, 2nd Duke of Buckingham, English statesman (d. 1687)
- January 12 - Charles Perrault, French folklorist (d. 1703)
- March 10 - Marcello Malpighi, Italian physician (d. 1694)
- March 17 - François Girardon, French sculptor (d. 1715)
- April 23 - Johann van Waveren Hudde, Dutch mathematician (d. 1704)
- May 17 - Archduke Ferdinand Charles of Austria, regent of the Tyrol (d. 1662)
- July 11 - Tokugawa Mitsukuni, Japanese warlord (d. 1701)
- August 29 - John Granville, 1st Earl of Bath, English royalist statesman (d. 1701)
- November 28 - John Bunyan, English writer (d. 1688)
- December 25 - Noël Coypel, French painter (d. 1707) See also :Category:1628 births.

Deaths

- March 12 - John Bull, English composer
- March 29 - Tobias Matthew, Archbishop of York (b. 1546)
- June 8 - Rudolph Goclenius, German philosopher (b. 1547)
- July 13 - Robert Shirley, English adventurer
- August 6 - Johannes Junius, Mayor of Bamberg (b. 1573)
- August 23 - George Villiers, 1st Duke of Buckingham, English statesman (b. 1592)
- September 30 - Fulke Greville, 1st Baron Brooke, English writer (b. 1554)
- October 16 - François de Malherbe, French poet and critic (b. 1555)
- November 15 - Roque Gonzales, Paraguayan missionary (b. 1576)
- November 16 - Paolo Quagliati, Italian composer
- Gregor Aichinger, German composer See also :Category:1628 deaths. Category:1628 ko:1628년 ms:1628

1658

Events

- January 13 - Edward Sexby, who had plotted against Oliver Cromwell, dies in Tower of London
- February 6 - Swedish troops of Charles X Gustav of Sweden cross The Great Belt (Storebælt) in Denmark over frozen sea
- May 1 - Publication of Hydriotaphia, Urn Burial and The Garden of Cyrus by Thomas Browne
- September 3 -Oliver Cromwell dies. His son Richard assumes his father's former position as Lord Protector of England, Scotland and Ireland.
- The peace between Sweden and Denmark was concluded in Roskilde with Treaty of Roskilde.
- France joins England in the war against Spain, which began in 1654. The Spanish were defeated at the Battle of the Dunes in June. England was then given Dunkirk for their assistance in the win.
- Portuguese traders are expelled from Ceylon by Dutch invaders.
- After his father Shah Jahan completes the Taj Mahal, his son Aurangzeb deposes him as ruler of the Mughal Empire.

Births

- February 18 - Charles-Irénée Castel de Saint-Pierre, French writer (d. 1743)
- March 5 - Antoine de Lamothe Cadillac, French explorer (d. 1730)
- April 19 - Johann Wilhelm, Elector Palatine (d. 1716)
- April 22 - Giuseppe Torelli, Italian composer (d. 1709)
- July 25 - Archibald Campbell, 1st Duke of Argyll, Scottish privy councillor (d. 1703)
- October 5 - Mary of Modena, queen of James II of England (d. 1718)
- October 19 - Adolf Friedrich II of Mecklenburg-Strelitz (d. 1704) See also :Category:1658 births.

Deaths

- January 7 - Theophilus Eaton, Connecticut colonist (b. 1590)
- January 13 - Edward Sexby, English Puritan soldier (b. 1616)
- April 7 - Juan Eusebio Nieremberg, Spanish mystic (b. 1595)
- April 29 - John Cleveland, English poet (b. 1613)
- September 3 - Oliver Cromwell, Lord Protector of England, Scotland, and Ireland (b. 1599)
- September 22 - Georg Philipp Harsdorffer, German poet (b. 1607)
- November 6 - Pierre du Ryer, French dramatist (b. 1606)
- November 8 - Witte Corneliszoon de With, Dutch naval officer (b. 1599)
- December 6 - Baltasar Gracián y Morales, Spanish writer (b. 1601) See also :Category:1658 deaths. Category:1658 ko:1658년

Blood

Blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells, platelets). Medical terms related to blood often begin in hemo- or hemato- (BE: haemo- and haemato-) from the Greek word "haima" for "blood". The main function of blood is to supply nutrients (oxygen, glucose) and constitutional elements to tissues and to remove waste products (such as carbon dioxide and lactic acid). Blood also enables cells (leukocytes, abnormal tumor cells) and different substances (amino acids, lipids, hormones) to be transported between tissues and organs. Problems with blood composition or circulation can lead to downstream tissue dysfunction.

Anatomy of blood

Blood is composed of several kinds of corpuscles; these formed elements of the blood constitute about 45% of whole blood. The other 55% is blood plasma, a yellowish fluid that is the blood's liquid medium. The normal pH of human arterial blood is approximately 7.40. Blood is about 7% of the human body weight [http://www.bloodcenters.org/aboutblood/bloodfacts.htm], so the average adult has a blood volume of about 5 liters, of which 2.7-3 liters is plasma. The combined surface area of all the erythrocytes in the human anatomy would be roughly 2,000 times as great as the body's exterior surface. The corpuscles are:
- Red blood cells or erythrocytes (96%). In mammals, these corpuscles lack a nucleus and organelles, so are not cells strictly speaking. They contain the blood's hemoglobin and distribute oxygen. The red blood cells (together with endothelial vessel cells and some other cells) are also marked by proteins that define different blood types.
- White blood cells or leukocytes (3.0%), are part of the immune system; they destroy infectious agents.
- Platelets or thrombocytes (1.0%) are responsible for blood clotting (coagulation) Blood plasma is essentially an aqueous solution containing 96% water, 4% blood plasma proteins, and trace amounts of other materials. Some components are:
- albumin
- blood clotting factors
- immunoglobulins (antibodies)
- hormones
- various other proteins
- various electrolytes (mainly sodium and chlorine) Together, plasma and corpuscles form a non-Newtonian fluid whose flow properties are uniquely adapted to the architecture of the blood vessels.

Physiology of blood

Production and degradation

Blood cells are produced in the bone marrow; the process is termed hematopoiesis. The proteinaceous component is produced overwhelmingly in the liver, while hormones are produced by the endocrine glands and the watery fraction maintained by the gut and the kidney. Blood cells are degraded by the spleen and the Kupffer cells in the liver. The liver also clears proteins and amino acids (the kidney secretes many small proteins into the urine). Erythrocytes usually live up to 120 days before they are systematically replaced by new erythrocytes created by the process of hematopoiesis.

Transport of oxygen

Blood oxygenation is measured with the partial pressure of oxygen. 98.5% of the oxygen is chemically combined with the Hb. Only 1.5% is physically dissolved. The hemoglobin molecule is the primary transporter of oxygen in mammals and many other species. With the exception of pulmonary and umbilical arteries and their corresponding veins, arteries carry oxygenated blood away from the heart and deliver it to the body via arterioles and capillaries, where the oxygen is consumed; afterwards, venules and veins carry deoxygenated blood back to the heart. Under normal conditions in humans, hemoglobin in blood leaving the lungs is about 96-97% saturated with oxygen; 'deoxygenated' blood returning to the lungs is still approximately 75% saturated.[http://home.hia.no/~stephens/ventphys.htm][http://groups.msn.com/TransplantSupportLungHeartLungHeart/oxygen2.msnw] A fetus, receiving oxygen via the placenta, is exposed to much lower oxygen pressures (about 20% of the level found in an adult's lungs) and so fetuses produce another form of hemoglobin with a much higher affinity for oxygen (hemoglobin F) in order to extract as much oxygen as possible from this sparse supply.[http://members.aol.com/Bio50/LecNotes/lecnot20.html]

Color

In humans and other hemoglobin-using creatures, oxygenated blood is a bright red in colour. Deoxygenated blood is a darker shade of red, which can be seen during blood donation and when venous blood samples are taken. However, due to an optical effect caused by the way in which light penetrates skin, veins typically appear blue.[http://www.people.virginia.edu/~rjh9u/blueblud.html] This has led to a common misconception that venous blood itself is blue.

Insects

In insects, the blood (more properly called hemolymph) is not involved in the transport of oxygen. (Openings called tracheae allow oxygen from the air to diffuse directly to the tissues). Insect blood moves nutrients to the tissues and removes waste products.

Small invertebrates

In some small invertebrates like insects, oxygen is simply dissolved in the plasma. Larger animals use respiratory proteins to increase the oxygen carrying capacity. Hemoglobin is the most common respiratory protein found in nature. Hemocyanin (blue) contains copper and is found in crustaceans and mollusks. It is thought that tunicates (sea squirts) might use vanabins (proteins containing vanadium) for respiratory pigment (bright green, blue, or orange). In many invertebrates, these oxygen-carrying proteins are freely soluble in the blood; in vertebrates they are contained in specialized red blood cells, allowing for a higher concentration of respiratory pigments without increasing viscosity or damaging blood filtering organs like the kidneys.

Transport of carbon dioxide

When systemic arterial blood flows through capillaries, carbon dioxide diffuses from the tissues into the blood. Some carbon dioxide is dissolved in the blood. Some carbon dioxide reacts with hemoglobin to form carbamino hemoglobin. The remaining carbon dioxide is converted to bicarbonate and hydrogen ions. Most carbon dioxide is transported through the blood in the form of bicarbonate ions.

Transport of hydrogen ions

Some oxyhemoglobin loses oxygen and becomes deoxyhemoglobin. Deoxyhemoglobin has a much greater affinity for H+ than does oxyhemoglobin so it binds most of the hydrogen ions.

Health and disease

Ancient medicine

Hippocratic medicine considered blood one of the four humors (together with phlegm, yellow bile and black bile). As many diseases were thought to be due to an excess of blood, bloodletting and leeching were a common intervention until the 19th century (it is still used for some rare blood disorders). In classical Greek medicine, blood was associated with air, springtime, and with a merry and gluttonous (sanguine) personality. It was also believed to be produced exclusively by the liver.

Diagnosis

Blood pressure and blood tests are amongst the most commonly performed diagnostic investigations that directly concern the blood.

Pathology

See also blood diseases Problems with blood circulation and composition play a role in many diseases.
- Wounds can cause major blood loss (see bleeding). The thrombocytes cause the blood to coagulate, blocking relatively minor wounds, but larger ones must be repaired at speed to prevent exsanguination. Damage to the internal organs can cause severe internal bleeding, or hemorrhage.
- Circulation blockage can also create many medical conditions from ischemia in the short term to tissue necrosis and gangrene in the long term.
- Hemophilia is a genetic illness that causes dysfunction in one of the blood's clotting mechanisms. This can allow otherwise inconsequential wounds to be life-threatening, but more commonly results in hemarthrosis, or bleeding into joint spaces, which can be crippling.
- Leukemia is a group of cancers of the blood-forming tissues.
- Major blood loss, whether traumatic or not (e.g. during surgery), as well as certain blood diseases like anemia and thalassemia, can require blood transfusion. Several countries have blood banks to fill the demand for transfusable blood. A person receiving a blood transfusion must have a blood type compatible with that of the donor.
- Blood is an important vector of infection. HIV, the virus which causes AIDS, is transmitted through contact between blood, semen, or the bodily secretions of an infected person. Hepatitis B and C are transmitted primarily through blood contact. Owing to blood-borne infections, bloodstained objects are treated as a biohazard.
- Infection of the blood is bacteremia or sepsis. Malaria and trypanosomiasis are blood-borne parasitic infections.

Treatment

Blood transfusion is the most direct therapeutic use of blood. It is obtained from human donors by blood donation. As there are different blood types, and transfusion of the incorrect blood may cause severe complications, crossmatching is done to ascertain the correct type is transfused. Other blood products administered intravenously are platelets, blood plasma, cryoprecipitate and specific coagulation factor concentrates. Many forms of medication (from antibiotics to chemotherapy) are administered intravenously, as they are not readily or adequately absorbed by the digestive tract. As stated above, some diseases are still treated by removing blood from the circulation.

Mythology and religion

Due to its importance to life, blood is associated with a large number of beliefs. One of the most basic is the use of blood as a symbol for family relationships; to be "related by blood" is to be related by ancestry or descendance, rather than marriage. This bears closely to bloodlines, and sayings such as "blood is thicker than water" and "bad blood", as well as "Blood brother".

Indo-European paganism

Among the Germanic tribes (such as the Anglo-Saxons and the Vikings), blood was used during the sacrifices, the Blóts. The blood was considered to have the power of its originator and after the butchering the blood was sprinkled on the walls, on the statues of the gods and on the participants themselves. This act of sprinkling blood was called bleodsian in Old English and the terminology was borrowed by the Roman Catholic Church becoming to bless and blessing. The Hittite word for blood, ishar was a cognate to words for "oath" and "bond", see Ishara.

Judaism

In Judaism, blood cannot be consumed even in the smallest quantity (Leviticus 3:17 and elsewhere); this is reflected in the dietary laws. Blood is purged from meat by salting and pickling. Other rituals involving blood are the covering of the blood of fowl and game after slaughtering (Leviticus 17:13); the reason given by the Torah is: "Because the soul of every animal is [in] his blood" (ibid 17:14), although from its context in Leviticus 3:17 it would appear that blood cannot be consumed because it is to be used in the sacrificial service (known as the korbanot), in the Temple in Jerusalem. Ironically, Judaism has historically been the religion to be most affected by blood libels.

Christianity

Christians believe that the Eucharist wine is, or represents, the blood of Jesus. This belief is rooted in the Last Supper as written in the four gospels of the Bible, in which Jesus stated to his disciples that the bread which they ate was his body, and the wine his blood. "This cup is the new testament in my blood, which is shed for you." (Luke 22:20, KJV). The accepted Christian belief is that Jesus' blood atoned for the sins of the people.

Jehovah's Witnesses

Jehovah's Witnesses are prohibited from eating blood and accepting tranfusions of whole blood or any of red cells, white cells, platelets or plasma. They are permitted to accept fractions, and the acute normovolemic hemodilution (ANH) and autologous blood salvage (cell saver) procedures.

Vampire legends

Vampires are fictional beings thought to cheat death by drinking the blood of the living.

Chinese and Japanese culture

In Chinese culture, it is often said that if a man's nose produces a small flow of blood, this signifies that he is experiencing sexual desire. This often appears in Chinese-language and Hong Kong films. This is also evident in Japanese culture and is parodied in anime and manga. Male characters will often be shown with a nosebleed if they have just seen a female nude or in little clothing, or if they have had an erotic thought or fantasy.

Microscope

A microscope (Greek: micron = small and scopos = aim) is an instrument for viewing objects that are too small to be seen by the naked or unaided eye. The science of investigating small objects using such an instrument is called microscopy, and the term microscopic means minute or very small, not easily visible with the unaided eye. In other words, requiring a microscope to examine. The most common type of microscope—and the first to be invented—is the optical microscope. This is an optical instrument containing one or more lenses that produce an enlarged image of an object placed in the focal plane of the lens(es). See also: Microscopy.

Simple optical microscope

A simple microscope, as opposed to a standard compound microscope (see below) with multiple lenses, is a microscope that uses only one lens for magnification. Van Leeuwenhoek's microscopes consisted of a single, small, convex lens mounted on a plate with a mechanism to hold the material to be examined (the sample or specimen). This use of a single, convex lens to magnify objects for viewing is still found in the magnifying glass, the hand-lens, and the loupe.

Compound optical microscope

The diagrams below show compound microscopes. In its simplest form—as used by Robert Hooke, for example—the compound microscope would have a single glass lens of short focal length for the objective, and another single glass lens for the eyepiece or ocular. Modern microscopes of this kind are usually more complex, with multiple lens components in both objective and eyepiece assemblies. These multi-component lenses are designed to reduce aberrations, particularly chromatic aberration and spherical aberration. In modern microscopes the mirror is replaced by a lamp unit providing stable, controllable illumination. Compound optical microscopes can magnify an image up to 1000× and are used to study thin specimens as they have a very limited depth of field. Typically they are used to examine a smear, a squash preparation, or a thinly sectioned slice of some material. With a few exceptions, they utilize light passing through the sample from below and special techniques are usually necessary to increase the contrast in the image to useful levels (see contrast methods). Typically, on a standard compound optical microscope, there are three objective lenses: a scanning lens (4×), low power lens (10×), and high power lens (40×). Advanced microscopes often have a fourth objective lens, called an oil immersion lens. To use this lens, a drop of oil is placed on top of the cover slip, and the lens moved into place where it is immersed in the oil. An oil immersion lens usually has a power of 100×. The actual power or magnification is the product of the powers of the ocular (eyepiece), usually about 10×, and the objective lens being used. To study the thin structure of metals (see metallography) and minerals, another type of microscope is used, where the light is reflected from the examined surface. The light is fed through the same objective using a semi-transparent mirror.

Stereo microscope

The stereo, binocular or dissecting microscope is designed differently from the diagrams above, and serves a different purpose. It uses two eyepieces (or sometimes two complete microscopes) to provide slightly different viewing angles to the left and right eyes. In this way it produces a three-dimensional (3-D) visualisation of the sample being examined. three-dimensional The stereo microscope is often used to study the surfaces of solid specimens or to carry out close work such as sorting, dissection, microsurgery, watch-making, small circuit board manufacture or inspection, and the like. Great working distance and depth of field here are important qualities for this type of microscope. Both qualities are inversely correlated with resolution: the higher the resolution (i.e., magnification), the smaller the depth of field and working distance. A stereo microscope has a useful magnification up to 100×. The resolution is maximally in the order of an average 10× objective in a compound microscope, and often much lower.

Special designs

Other types of optical microscope include:
- the inverted microscope for studying samples from below; useful for cell cultures in liquid;
- the student microscope designed for low cost, durability, and ease of use; and
- the research microscope which is an expensive tool with many enhancements.
- the petrographic microscope whose design usually includes a polarizing filter, rotating stage and gypsum plate to facilitate the study of minerals or other crystalline materials whose optical properties can vary with orientation.

Optical resolution

A lens magnifies by bending light (see refraction). Optical microscopes are restricted in their ability to resolve features by a phenomenon called diffraction which, based on the numerical aperture (NA or

A_N

) of the optical system and the wavelengths of light used (

\lambda

), sets a definite limit (d) to the optical resolution. Assuming that optical aberrations are negligible, the resolution (d) is given by: :

d = \frac

Usually, a

\lambda

of 550 nm is assumed, corresponding to green light. With air as medium, the highest practical

A_N

is 0.95, and with oil, up to 1.5. Due to diffraction, even the best optical microscope is limited to a resolution of 0.2 micrometres.

History of the microscope

micrometre.]] :See timeline of microscope technology. It is impossible to say who invented the compound microscope. Dutch spectacle-makers Hans Janssen and his son Zacharias Janssen are often said to have invented the first compound microscope in 1590, but this was a declaration by Zacharias Janssen himself halfway through the 17th century. The date is certainly not likely, as it has been shown that Zacharias Janssen actually was just about born in 1590. Another favorite for the title of 'inventor of the microscope' was Galileo Galilei. He developed an occhiolino or compound microscope with a convex and a concave lens in 1609. Galilei´s microscope was celebrated in the ´Lynx academy´ founded by Federico Cesi in 1603. Francesco Stelluti´s drawing of three bees were part of pope Urban VIII´s seal, and count as the first microscopic figure published (see Stephen Jay Gould, The Lying stones of Marrakech, 2000). Christiaan Huygens, another Dutchman, developed a simple 2-lens ocular system in the late 1600's that was achromatically corrected and therefore a huge step forward in microscope development. The Huygens ocular is still being produced to this day, but suffers from a small field size, and the eye relief is uncomfortably close compared to modern widefield oculars. Anton van Leeuwenhoek (1632-1723) is generally credited with bringing the microscope to the attention of biologists, even though simple magnifying lenses were already being produced in the 1500's, and the magnifying principle of water-filled glass bowls had been described by the Romans (Seneca). Van Leeuwenhoek's home-made microscopes were actually very small simple instruments with a single very strong lens. They were awkard in use but enabled van Leeuwenhoek to see highly detailed images, mainly because a single lens does not suffer the lens faults that are doubled or even multiplied when using several lenses in combination as in a compound microscope. It actually took about 150 years of optical development before the compound microscope was able to provide the same quality image as van Leeuwenhoek's simple microscopes. So although he was certainly a great microscopist, van Leeuwenhoek is, contrary to widespread claims, certainly not the inventor of the microscope.

Other types of microscopes

Anton van Leeuwenhoek See also microscopy
- Atom probe
- Atomic force microscope
- Darkfield microscope
- Electron microscope
- Field ion microscope
- Field emission microscope
- Phase contrast microscope, see Frits Zernike
- Scanning tunneling microscope
- Virtual microscope
- X-ray microscope
- Total internal reflection fluorescence microscope
- Confocal laser scanning microscopy

External links

- [http://gerdbreitenbach.de/crystal/crystal.html A virtual polarization microscope] (requires Java)
- [http://www.opticsplanet.com/info/htb_micorscope.shtml How To Buy A Microscope]
- [http://www.microscopy-uk.org.uk/mag/indexmag.html Micscape] - a monthly magazine directed towards the amateur microscopist
- [http://www.biologie.uni-hamburg.de/b-online/e03/03.htm Microscopy]
- [http://www.microscopes-online.info Microscope Directory]
- [http://web.uvic.ca/ail/techniques/scope_basics.html the optics of the microscope]
- [http://micro.magnet.fsu.edu/primer/index.html Optical microscopy primer]
- [http://www.rms.org.uk/ Royal Microscopical Society]
- [http://www.mcri.org/McRI_products.html The Microscope] - quarterly journal
- [http://www.ecoscope.com/cybermic/index.htm Virtual microscope on plankton]
- [http://www.musoptin.com/mikro1.html Antique German microscopes] history of continental microscopes illustrated with 2000 photos (in German)
- [http://users.bestweb.net/~wissner/page2.html Early American made microscopes ] Antique American made microscopes and the makers.
- [http://users.bestweb.net/~wissner/kellner/kellner1.html Some Early Microscopes from the Optical Institute in Wetzlar] Microscope history. Category:Microscopes Category:Optical devices ko:현미경 ms:Mikroskop ja:顕微鏡 simple:Microscope th:กล้องจุลทรรศน์

Robert Hooke

Robert Hooke, FRS (July 18, 1635 - March 3, 1703), one of the greatest experimental scientists of the seventeenth century, played an important role in the scientific revolution. Born in Freshwater on the Isle of Wight, Hooke received his early education at Westminster School. In 1653, Hooke won a place at Christ Church, Oxford. There he met Robert Boyle, and gained employment as his assistant. It is possible that Hooke formally stated Boyle's Law, as Boyle was not a mathematician. In 1660, he discovered Hooke's law of elasticity, which describes the linear variation of tension with extension in an elastic spring. In 1662, Hooke gained appointment as Curator of Experiments to the newly founded Royal Society, and took responsibility for experiments performed at its meetings. In 1665 he published a book entitled Micrographia, which contained a number of microscopic and telescopic observations, and some original biology. Indeed, Hooke coined the biological term cell -- so called because his observations of plant cells reminded him of monks' cells. Also in 1665 he gained appointment as Professor of Geometry at Gresham College. Robert Hooke also achieved fame as Surveyor to the City of London and chief assistant of Christopher Wren, helping to rebuild London after the Great Fire in 1666. He worked on designing the Royal Greenwich Observatory and the infamous Bethlem Royal Hospital (which became known as 'Bedlam'). He died in London in 1703. Although he was wealthy from his work in the City, he never married. No authenticated portrait of him survives, although the historian Lisa Jardine claims one portrait of John Ray represents Robert Hooke, and a seal used by Hooke displays a man's head that some have argued portrays Hooke. Both these claims remain in dispute, however.

Achievements

John Ray.]] In addition to the book Micrographia and Hooke's Law, Hooke invented the anchor escapement and may also have invented the balance spring before Christiaan Huygens. Devices known as escapements regulate the rate of a watch or clock, and the anchor escapement represented a major step in the development of accurate watches. The balance spring also regulates the flow of energy from the mainspring of a timepiece. It coils and uncoils with a natural periodicity, allowing for fine adjustment of the period of ticks. Modern spring watches still use balance springs, and derivative designs of Hooke's anchor escapement remain in common use. Historians sometimes credit Hooke with inventing the compound microscope, a design consisting of multiple lenses (usually three - an eyepiece, a field lens and an objective). While he did give much advice on new microscope designs to the instrument-maker Christopher Cock, this attribution appears incorrect, since Zacharias Janssen had already assembled compound microscopes in 1590. However, Hooke's microscopes achieved 30x magnification, which far outstripped the capabilities of any previous instruments. Hooke once called his compound microscopes "offensive to my eye" and "much strained and weakened the sight". Leeuwenhoek found his animalcules and Hooke was asked to confirm his findings. Hooke's other significant achievements include the construction of the first Gregorian reflecting telescope and the discovery of the first binary star. He also receives credit with inventing the first practical universal joint, sometimes called the Hooke joint, although the Italian mathematician Girolamo Cardano had proposed the idea about a century earlier and may or may not have built one. Hooke also experimentally demonstrated the inverse-square law of gravity, but lacked the mathematics to formally prove it.

Hooke and Newton

Robert Hooke and Isaac Newton entertained a considerable mutual dislike for each other. They fell out in 1672 when Hooke criticized Newton's presentation showing that prisms split white light rather than modifying it. Newton expressed fury that Hooke seemed unable to grasp his ground-breaking discovery, and threatened to leave the Royal Society. Relations between the men grew worse as time progressed. In 1679, Hooke wrote to Newton advocating an inverse square law of gravitation, though he lacked the mathematical ability to formally prove it. When Newton published his Principia Mathematica in 1687, including a proof of an inverse square law, he failed to credit Hooke at all. It is possible that this dispute may be overplayed: Gunther suggests that the two men held each other in some regard until quite late, citing as evidence their correspondence over matters such as the inverse-square law of gravitation, which Hooke (an undoubtedly gifted experimenter) had demonstrated. The famous Newton quote, "If I have seen further, it is by standing on the shoulders of giants", appeared originally in a letter to Hooke, and this has been interpreted as a sarcastic remark directed against Hooke. This is somewhat speculative: Hooke and Newton had exchanged many letters in tones of mutual regard, and Hooke was not of particularly short stature, although he was of slight build and had been afflicted from his youth with a severe stoop. Part of the problem was caused by Newton's retreat to Cambridge during the years around the Plague and Great Fire. Hooke remained in London, demonstrating regularly at the Royal Society, while Newton's work often took longer to reach the Society. Hooke made what are apparently barbed references to the benefits of attending the Society in person rather than receiving the reports at a later date. At a time when science was progressing by leaps and bounds it was inevitable that two men with such similar interests would come up with similar ideas. Whether Hooke or Newton first invented the reflecting telescope is a matter of conjecture, but it is the case that Hooke did demonstrate what is now known as the Newtonian telescope some time before Newton is credited with inventing it, as well as documenting "Newton's rings" before Newton did. Newton's animosity towards Hooke extended to the removal of Hooke's portrait in the Royal Society (long believed destroyed but recently rediscovered) and an attempt (prevented) to have Hooke's papers in the Society burned. It is probably thanks to Newton that Hooke's name remained relatively unknown until the latter part of the 20th Century, although Hooke's own unsympathetic character was undoubtedly also a factor: he was known to have had acrimonious exchanges with many other contemporaries, and to bear grudges.

Hooke the architect

standing on the shoulders of giants Robert Hooke was an important architect. He was the official London Surveyor after the Great Fire of 1666. As well as the Bethlem Royal Hospital, other buildings designed by Hooke include: The Royal College of Physicians (1679); Ragley Hall in Warwickshire; and the church at Willen, Buckinghamshire. Hooke's collaboration with Christopher Wren was particularly fruitful and yielded and The Royal Observatory at Greenwich, The Monument (to the Great Fire) and St Paul's Cathedral, whose dome uses a method of construction conceived by Hooke. In the reconstruction after the Great Fire, Hooke proposed redesigning London's streets on a grid pattern with wide boulevards and arteries along the lines of the Champs-Élysées, (this pattern was subsequently used for Liverpool and many American cities), but was prevented by problems over property rights. Many property owners were surreptitiously shifting their boundaries and disputes were rife. So London was rebuilt along the original mediaeval streets. It is interesting to note that the modern-day curse of congestion in London has its origin in petty disputes in the 17th Century.

Mass Media

Robert Hooke is one of many real-life personages featured in the historical adventure novels The Baroque Cycle by American author Neal Stephenson; Hooke's skill in the sciences and surgical arts are used to great (and often darkly comedic) effect throughout the cycle.

Books

- Early Science in Oxford vol vii, Dr. R. T. Gunther, ed., privately printed, 1923-67.
- Robert Hooke, Margaret 'Espinasse. William Heinmann Ltd, 1956.
- The Curious Life of Robert Hooke: The Man who Measured London, Lisa Jardine. Harper Collins Publishers, 2003. ISBN 0007149441.
- London's Leonardo: The Life and Work of Robert Hooke, Jim Bennett, Michael Cooper, Michael Hunter and Lisa Jardine. Oxford University Press, 2003. ISBN 0198525796.
- England's Leonardo: Robert Hooke and the Seventeenth-century Scientific Revolution, Allan Chapman. Institute of Physics Publishing, 2004. ISBN 0750309873.
- Robert Hooke and the English Renaissance, Allan Chapman and Paul Kent (editors). Gracewing, 2005. ISBN 0852445873.

External links

- [http://www.roberthooke.org.uk roberthooke.org.uk]
-
- [http://freespace.virgin.net/ric.martin/vectis/hookeweb/roberthooke.htm Hooke Timeline]
- [http://physics.iop.org/IOP/Press/PR1203.html Robert Hooke – the face of England's Leonardo?] from the Institute of Physics
- [http://www.rod.beavon.clara.net/leonardo.htm England's Leonardo] lecture on Robert Hooke
- [http://archive.museophile.org/ox/univ-col/boyle-hooke.html Robert Boyle and Robert Hooke] Hooke, Robert Hooke, Robert Hooke, Robert Hooke, Robert Hooke, Robert Hooke, Robert Hooke, Robert Hooke, Robert Hooke, Robert Hooke, Robert ms:Robert Hooke ja:ロバート・フック

Cork (material)

Cork material is a subset of generic cork tissue, harvested for commercial use primarily from the Cork Oak tree, Quercus suber, with Portugal producing most cork worldwide. Cork's elasticity combined with its near-impermeability makes it suitable as a material for bottle stoppers, especially for wine bottles. Cork stoppers represent about 60% of all cork based production. Cork's low density makes it a suitable material for fishing floats and buoys. Sheets of cork, often the byproduct of more lucrative stopper production, are used to make floor tiles and bulletin boards. The cork industry is generally regarded as environmentally friendly. The sustainability of its production and the easy recycling of cork's products and by-products are two of its most distinctive aspects. Cork demand has increased due to a larger proportion of wine being sealed with cork rather than being sold in bulk. Since a tree's bark can only be harvested once a decade or so, supply is highly inelastic. Top quality corks are quite expensive, so cheaper brands have switched to lower quality cork, synthetic plastic stoppers, screwcaps, or other closures. These also eliminate cork taint. The synthetic stoppers also do not dry out and shrink so the bottles do not have to be on their sides to prevent the wine from oxidizing. However, on the down side, both synthetic stoppers and screwcaps require different winemaking methods to some extent, as sulfur dioxide (SO₂) levels need to be different, and there may be different wine faults due to oxidation or reduction. Cork contamination with harmless but foul-smelling trichloroanisole (TCA) is one of the primary causes of cork taint in wine. Cork related trichloroanisole has been reduced by means of new and more reliable production methods, such as changes in the bleaching process. Recently cork has also been used in rocket technology due to its fire resistance. It can also be used as bricks for the outer wall of a house (this was done in Portugal's pavilion at Expo 2000). Note that the Cork Oak is unrelated to the "cork trees" (Phellodendron), which have corky bark but are not used for cork production.

External link

- [http://www.corkfacts.com/natlcrk11.htm Cork production]
- [http://www.corksupplyusa.com Cork Supply USA]
- [http://www.iprocor.org Instituto de Promoción del Corcho, Extremadura (Spain)] Category:Wine Category:Arabic words ms:Gabus ja:コルク

Francesco Redi

Francesco Redi (February 18/19, 1626 – March 1, 1697) was a physician born in Arezzo, Italy. He is most well-known for his experiment in 1668 which is regarded as a one of the first steps in refuting abiogenesis. At the time, prevailing wisdom was that maggots formed naturally from rotting meat. In the experiment, Redi took three jars and put meat in each. He tightly sealed one, left one open, and covered the top of another with gauze. Maggots appeared on the meat in the open jar, but not in the sealed one, and maggots also hatched on the gauze cover of the gauze jar. He continued his experiments, by capturing the maggots and waiting for them to hatch, which they did, becoming common flies. Also, when dead flies or maggots were put in sealed jars with meat, no maggots appeared. But, when the same thing was done with living flies, maggots did appear. (Experiments on the generation of insects by Francesco Redi, trans. by M. Bigelow, Chicago, 1909) Redi was also a poet, his best known work being Bacchus in Tuscany. A crater on Mars was named in his honor.

External link

[http://www.newadvent.org/cathen/12687b.htm Francesco Redi] entry at the Catholic Encyclopedia Redi, Francesco Redi, Francesco Redi, Francesco

Maggot

The word maggot can mean:-
- The larva of a fly: see Fly.
- See maggot therapy.
- A white maggot is an Australian derogatory term given to umpires in Australian Football League.
- The Maggot is an enemy in the computer game Doom 3.
- A Maggot is a novel by British author John Fowles, published in 1985.
- Maggot Brain is a 1971 album by the American funk band Funkadelic.
- The Apple maggot Rhagoletis pomonella, also known as railroad worm, is a pest of several fruits, mainly apples.
- For the maggot pattern on British neolithic pottery, see Peterborough ware.
- Farmer Maggot is a character in the Lord of the Rings by J. R. R. Tolkien.
- maggoted is a slang term for drunkenness: see List of slang terms for drunkenness.
- A Slipknot fan is commonly called a "Maggot".

Anton van Leeuwenhoek

Anton van Leeuwenhoek (October 24, 1632 - August 30, 1723, full name Thonius Philips van Leeuwenhoek (pronounced 'Lowenhook') was a tradesman and scientist from Delft, Netherlands. He was known as "the Father of Microbiology". Born the son of a basket maker, at age 16 he secured an apprenticeship with a Scottish cloth merchant in Amsterdam. He is best known for his contribution to the improvement of the microscope and for his contributions towards the establishment of microbiology. Using his handcrafted microscopes he was the first to observe and describe single celled organisms which he first referred to as animalcules, and which we now refer to as microorganisms. He was also the first to record microscopic observations of muscle fibers, bacteria, spermatozoa and blood flow in capillaries (small blood vessels). Van Leeuwenhoek's early discoveries in the field of microbiology can be likened to Galileo's early discoveries in the field of astronomy. Both men used the newly improved optical technologies of their day to make major discoveries that entirely overturned traditional beliefs and theories in their respective fields, and both men were initially met with strong skepticism and resistence to the inevitable conclusions that their discoveries led to. Ultimately van Leeuwenhoek was more fortunate than Galileo in that his discoveries were eventually widely accepted and applauded in his lifetime, whereas Galileo's were not. During his lifetime van Leeuwenhoek ground over 500 optical lenses. He also created over 400 different types of microscopes, only nine of which still exist today. His microscopes were made of silver or copper metal frames holding hand-ground lenses. Those that survived the years are able to magnify up to 270 times. It is suspected, though, that van Leeuwenhoek possessed some microscopes that could magnify up to 500 times.

Early involvement with the microscope

In 1648 in Amsterdam van Leeuwenhoek saw his first simple microscope, a magnifying glass mounted on a small stand used by textile merchants capable of magnifying to a power of 3. He soon acquired one for his own use. In 1654, he left Amsterdam, moved back to Delft and started his own lucrative drapery business there. In 1660, he was appointed chamberlain of the Lord Regents of Delft. It is believed that soon after 1665 he read a book by Robert Hooke, titled Micrographia. His reading of Hooke's book is believed to have roused an interest in van Leeuwenhoek to use his microscopes for the purpose of investigating the natural world beyond the mere quality of the fabrics he sold. In 1669 he obtained a degree in geography, leading to his later appointment as geographer in 1679. His interest in microscopy steadily grew until he was spending most of his nights and free time grinding his own lenses, improving the quality of his microscopes, and studying everything he could beneath them. He also carefully documented many of his observations. He soon developed what is believed to have been the highest powered microscopes of his day, magnifying up to 500 times. He retained some of his methods of microscope construction in secret, "which I only keep for myself". While it is agreed that many of his observations would have required a 500 power microscope, exactly how he constructed such a microscope remains unknown to this day.

Eventual recognition by the English Royal Society

After his important improvements to the microscope, and his thorough use of it, he was introduced via correspondence to the English Royal Society by the famous Dutch Physician Regnier de Graaf. He soon began to send copies of his recorded microscopic observations to the Royal Society. In 1673 his earliest observations were published by the Royal Society in its journal: Philosophical Transactions. Amongst these published observations were Van Leeuwenhoek's accounts of bee mouthparts and stings... . Despite the initial success of Van Leeuwenhoek's relationship with the Royal Society, this relationship was soon severely strained. In 1676 his credibility was questioned when he sent the Royal Society a copy of his first observations of microscopic life forms. Heretofore, the existence of such life forms was entirely unknown. Thus, even with his established reputation with the Royal Society as a reliable observer, his observations of microscopic life were initially met with extreme ridicule. Following is a transcript of the reply of the Royal Society to his first report of the existence of microscopic life:

20th of October, 1676
Dear Mr. Anthony van Leeuwenhoek,
Your letter of October 10th has been received here with amusement. Your account of myriad 'little animals' seen swimming in rainwater, with the aid of your so-called 'microscope,' caused the members of the society considerable merriment when read at our most recent meeting. Your novel descriptions of the sundry anatomies and occupations of these invisible creatures led one member to imagine that your 'rainwater' might have contained an ample portion of distilled spirits--imbibed by the investigator. Another member raised a glass of clear water and exclaimed, 'Behold, the Africk of Leeuwenhoek.' For myself, I withhold judgment as to the sobriety of your observations and the veracity of your instrument. However, a vote having been taken among the members--accompanied I regret to inform you, by considerable giggling--it has been decided not to publish your communication in the Proceedings of this esteemed society. However, all here wish your 'little animals' health, prodigality and good husbandry by their ingenious 'discoverer.'

Hendrik Oldenburg
Secretary of the Royal Society, London

Despite the less than favorable reaction of the Royal Society to his first reports of microscopic life, he remained undaunted, and continued to insist to the Royal Society that his observations were accurate, true and valid. He also continued his microscopic investigations without interruption. Eventually, in the face of Van Leeuwenhoek's insistence, the Royal Society arranged to send an English vicar, as well as a team of respected jurists and doctors to Delft, Holland to determine whether it was in fact Van Leeuwenhoek's drinking habits, or perhaps the Royal Society's theories of life that might require reform. Finally in 1680, Van Leeuwenhoek's observations were fully vindicated by the Society. Van Leeuwenhoek's vindication resulted in his appointment as a member of the Royal Society in that year. After his appointment to the Society, he wrote approximately 560 letters to the Society and other scientific institutions over a period of 50 years. These letters dealt with the subjects he had investigated. Amongst Van Leeuwenhoek's many discoveries are: In 1674 he discovered infusoria (dated zoölogical category,) in 1676 he discovered bacteria, in 1677 he discovered spermatozoi and in 1682 he discovered the banded pattern of muscular fibers. He died at the age of 92, on August 30, 1723.

Possible Vermeer connection

Van Leeuwenhoek was a contemporary of that other famous Delft citizen, painter Johannes Vermeer, who was baptized just four days earlier. It has been suggested that he is the man portrayed in two of Vermeer's paintings of the late 1660s, The astronomer and The geographer. Because they were both relatively important men in a city with only 24,000 inhabitants, it is possible that they were at least acquaintances. Also, it is known that Van Leeuwenhoek acted as the executor when the painter died in 1675. However, others argue that there appears to be little physical similarity.

Notes

The given name Anton can also be found written as Anthon, Anthony, Antonie, Antony, Anthonie, Antoni, Antonio and Anthoni.

External links

- [http://www.euronet.nl/users/warnar/leeuwenhoek.html Dutch online biography of van Leeuwenhoek]
- [http://essentialvermeer.20m.com/dutch-painters/dutch_art/leeuwenhoek.htm Vermeer connection website]

References

- Van Berkel, K. (February 24 1996). Vermeer, Van Leeuwenhoek en De Astronoom. Vrij Nederland (Dutch magazine), p. 62–67.
- http://www.adherents.com/people/pl/Antony_van_Leeuwenhoek.html
- A. Schierbeek, PhD, Editor-in-Chief of the Collected Letters of A. v. Leeuwenhoek, Formerly Lecturer in the History of Biology in the University of Leyden, Measuring the Invisible World: The Life and Works of Antoni van Leeuwenhoek F R S, Abelard-Schuman (London and New York, 1959), QH 31 L55 S3, LC 59-13233 . This book (223 pp.) contains excerpts of Leeuwenhoek’s letters and focuses on his priority in several new branches of science, but makes several important references to his spiritual life and motivation.
- http://www.creationsafaris.com/wgcs_2.htm Leeuwenhoek, Anton van Leeuwenhoek, Anton van Leeuwenhoek, Anton van Leeuwenhoek, Anton van Leeuwenhoek, Anton van ja:レーウェンフック

Wikipedia:Featured article removal candidates/war elephant

war elephant

:Article is still a featured article. Jumping on the "no elephants in FA" bandwagon, this recent main-page feature is remarkably low on detail for such a colorful subject, needs copyediting and subsectioning, and needs deeper linking to species and military articles. I have suggested it for Peer Review, and think it should be removed from FA in the meanwhile. +sj + 20:23, 10 Aug 2004 (UTC) :While not one of our best FAs, it still looks good enough to me. --mav 17:40, 3 Sep 2004 (UTC) ::I agree with Mav's assessment. →Raul654 18:45, Sep 3, 2004 (UTC) :Keep feature status -- Chris 73 Talk 09:27, Sep 5, 2004 (UTC)

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