Leeuwenhoek, Anton van (1632-73), a noted microscopist, was born at Delft. His practice as a glass-grinder led him to see the advantage of employing a single lens of short focus in microscopic work. In 1673 he was introduced by De Graaf to the Royal Society, and gave an account of his views in their Transactions, and in 1680 he was made a fellow. Among his many discoveries, perhaps the most important was that of capillary circulation, which he demonstrated on various animals, and the different shapes of blood discs. He also strongly advocated the theory "omne vivum ex ovo" in opposition to the supporters of the theory of spontaneous generation. He made discoveries, too, relating to the teeth, the lens of the eye, the epidermis, spermatozoa, scales on insects wings, spiders, fleas, trees, and plants. The most complete edition of his works was published at Leyden (1719-22).