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LEEUWENHOEK, or LEUWENHOEK, ANTHONY V...
Online EncyclopediaOriginally appearing in Volume
V16,
Page 371
of the 1911 Encyclopedia Britannica.
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See also: LEEUWENHOEK, or LEUWENHOEK, See also:ANTHONY See also:VAN (1632–1723) , Dutch microscopist, was See also:born at See also:Delft on the 24th of See also:October 1632. For a See also:short See also:time he was in a See also:merchant's See also:office in See also:Amsterdam, but See also:early devoted himself to the manufacture of microscopes and to the study of the See also:minute structure of organized bodies by their aid. He appears soon to have found that single lenses of very short See also:focus were preferable to the See also:compound microscopes then in use; and it is clear from the discoveries he made with these that they must have been of very excellent quality. His discoveries were for the most See also:part made public in the Philosophical Transactions of the Royal Society, to the See also:notice of which See also:body he was introduced by R. de Graaf in 1673, and of which he was elected a See also:fellow in 1680. He was chosen a corresponding member of the See also:Paris See also:Academy of Sciences in 1697. He died at his native See also:place on the 26th of See also:August 1723. Though his researches were not conducted on any definite scientific See also:plan, his See also:powers of careful observation enabled him to make many interesting discoveries in the minute See also:anatomy of See also:man, the higher animals and See also:insects. He confirmed and extended M. See also:Malpighi's demonstration of the See also:blood capillaries in 1668, and six years later he gave the first accurate description of the red blood corpuscles, which he found to be circular in man but See also:oval in frogs and fishes. In 1677 he described and illustrated the spermatozoa in See also:dogs and other animals, though in this See also:discovery See also:Stephen See also:Hamm had anticipated him by a few months; and he investigated the structure of the See also:teeth, crystalline See also:lens, muscle, &c. In 168o he noticed that yeast consists of minute globular particles, and he described the different structure of the See also:stem in monocotyledonous and dicotyledonous See also:plants. His researches in the See also:life-See also:history of various of the See also:lower forms of See also:animal life were in opposition to the See also:doctrine that they could be " produced spontaneously, or bred from corruption." Thus he showed that the weevils of See also:granaries, in his time commonly sup-posed to be bred from See also:wheat, as well as in it, are grubs hatched from eggs deposited by winged insects.His See also: chapter on the See also:flea,in which he not only describes its structure, but traces out the whole history of its metamorphoses from its first emergence from the See also:egg, is full of See also:interest—not so much for the exactness of his observations, as for its incidental See also:revelation of the extraordinary See also:ignorance then prevalent in regard to the origin and See also:propagation of " this minute and despised creature," which some asserted to be produced from See also:sand, others from dust, others from the dung of pigeons, and others from urine, but which he showed to be "endowed with as See also:great perfection in its See also:kind as any large animal," and proved to breed in the See also:regular way of winged insects. He even noted the fact that the pupa of the flea is sometimes attacked and fed upon by a See also:mite—an observation which suggested the well known lines of See also:Swift. His See also:attention having been See also:drawn to the blighting of the See also:young shoots of See also:fruit-trees, which was commonly attributed to the ants found upon them, he was the first to find the See also:Aphides that really do the See also:mischief; and, upon searching into the history of their See also:generation, he observed the young within the bodies of their parents. He carefully studied also the history of the See also:ant and was the first to show that what had been commonly reputed to be " ants' eggs " are really their pupae, containing the perfect See also:insect nearly ready for emersion, whilst the true eggs are far smaller, and give origin to " maggots " or larvae. Of the See also:sea-See also:mussel, again, and other See also:shell-See also:fish, he argued (in reply to a then See also:recent See also:defence of See also:Aristotle's doctrine by F. Buonanni, a learned Jesuit of See also:Rome) that they are not generated out of the mud or sand found on the seashore or the beds of See also:rivers at See also:low See also:water, but from spawn, by the regular course of generation; and he maintained the same to be true of the fresh-water mussel (Unio), whose ova he examined so carefully that he saw in them the rotation of the embryo, a phenomenon supposed to have been first discovered See also:long afterwards. In the same spirit he investigated the generation of eels, which were at that time supposed, not only by the ignorant vulgar, but by " respectable and learned men," to be produced from See also:dew without the See also:ordinary See also:process of generation. Not only was See also:lie the first discoverer of the rotifers, but he showed " how wonderfully nature has provided for the preservation of their See also:species," by their tolerance of the drying-up of the water they inhabit, and the resistance afforded to the evaporation of the fluids of their bodies by the impermeability of the casing in which they then become enclosed. " We can now easily conceive," he says, " that in all See also:rain-water which is collected from gutters in cisterns, and in all See also:waters exposed to the See also:air, animalcules may be found; for they may be carried thither by the particles of dust blown about by the winds." Lecuwenhoek's contributions to the Philosophical Transactions amounted to one See also:hundred and twelve; he also published twenty-six papers in the See also:Memoirs of the Paris Academy of Sciences. Two collections of his See also:works appeared during his life, one in Dutch (See also:Leiden and Delft, 1685–1718), and the other in Latin (See also:Opera omnia s. Arcana naturae ope exactissimorum microscopiorum selecta, Leiden, 1715–1722) ; and a selection from them was translated by S. See also:Hoole and published in See also:English (See also:London, 1798–1781).Additional information and CommentsThere are no comments yet for this article.
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