302 years ago today, on August 27, 1723 (July 27, 1723), Dutch biologist Leeuwenhoek died. On August 27, 1723, Dutch biologist Leeuwenhoek died. Anton Leeuwenhoek (1632-1723) Dutch microscopist and naturalist. Born in Delft. Self-taught. Worked as an apprentice, opened a grocery store, and worked as a janitor at the town hall. His greatest contribution was the use of a homemade microscope to discover the microbial world (then known as microfauna). His microscope had a magnification of 50-300 times and a simple structure. Only one lens was installed between two metal sheets. In front of the lens, there was a short metal rod. At the tip of the rod, the sample to be observed was placed, and the focal length was adjusted by focusing the spiral. Using this microscope, Anton Leeuwenhoek clearly saw bacteria and protozoa. For the first time, he revealed a new biological world - the microbial world. Due to his epoch-making contributions, he was elected a member of the Royal Society in 1680. He loved making magnifying glasses and microscopes, and made more than 400 microscopes and magnifying glasses in his lifetime. He bequeathed to the Royal Society a cabinet containing 26 instruments and some lenses. His main work was a collection of essays entitled "The Mysteries of Nature" (1695-1719). In 1688, microvessels were discovered by observing the tadpole tail with a microscope, and together with Malpiki, Harvey's theory of blood circulation was confirmed. Protozoa and sperm were discovered in 1675; bacteria were discovered in 1681, laying the foundation for microbiology and medicine. In 1723, at the age of 91, Leeuwenhoek, on his deathbed, gave part of his own microscopes, magnifying glasses, and the secret of making excellent instruments to the Royal Society.