In Van Leeuwenhoek examined fresh semen, in which he observed living spermatozoa. His unique observations on microorganisms probably began in , when he examined water from a lake near Delft. He gave the first description of the common green alga Spirogyra but also observed smaller organisms, which were probably free-living protozoa.
Van Leeuwenhoek also discovered parasitic protozoa, describing the flagellate Giardia in a sample of his feces, which also contained bacteria which can be identified as Spirochaeta. In a letter written in he describes and illustrates five different kinds of bacteria present in his own mouth: these can readily be identified as a motile bacillus, Selenomonas sputigena, a micrococcus, Leptothrix buccalis, and a spirochete.
He continued to make observations on microorganisms until , and while studying free-living protozoa, he also discovered other organisms such as Volvox, Hydra, and rotifers.
Van Leeuwenhoek's discovery of microorganisms has tended to overshadow his other work, which has not received full recognition. He was one of the first comparative anatomists, since he often followed a structure in several different species.
As a pioneer of microdissection, he succeeded in obtaining results which are remarkable even by modern standards. Between and he carried out a series of microdissections, mainly on insects, and one of his most original discoveries was parthenogenesis in aphids. The parent aphids did not contain eggs, but young aphids just like the parent. Van Leeuwenhoek's insatiable curiosity, coupled with remarkable tenacity and skill, makes him one of the most outstanding scientists of all time.
In his own modest way he realized how rare his gifts were and also that other people's motives were not always those of a true student of nature.
In a letter he noted: "Some go to make money out of science, or to get a reputation in the learned world. But in lens-grinding and discovering things hidden from our sight, these count for nought.
And I am satisfied too that not one man in a thousand is capable of such study, because it needs much time … and you must always keep thinking about these things if you are to get any results. And over and above all, most men are not curious to know: nay, some even make no bones about saying, What does it matter whether we know this or not? The Collected Letters of Antoni van Leeuwenhoek was edited by a committee of Dutch scientists 8 vols.
In , he reported his first observations - bee mouthparts and stings, a human louse and a fungus - to the Royal Society. He was elected a member of the society in and continued his association for the rest of his life by correspondence. In , van Leeuwenhoek observed water closely and was surprised to see tiny organisms - the first bacteria observed by man.
His letter announcing this discovery caused widespread doubt at the Royal Society but Robert Hooke later repeated the experiment and was able to confirm his discoveries. As well as being the father of microbiology, van Leeuwenhoek laid the foundations of plant anatomy and became an expert on animal reproduction.
He discovered blood cells and microscopic nematodes, and studied the structure of wood and crystals. He also made over microscopes to view specific objects. He also discovered sperm, which he considered one of the most important discoveries of his career, and described the spermatozoa from molluscs, fish, amphibians, birds and mammals, coming to the novel conclusion that fertilisation occurred when the spermatozoa penetrated the egg.
Some people had to come to him to see his work in person. Just 11 of Leeuwenhoek's microscopes exist today. His instruments were made of gold and silver, and most were sold by his family after he died in Other scientists did not use his microscopes, as they were difficult to learn to use. Some improvements to the device occurred in the s, but big improvements that led to today's compound microscopes didn't happen until the middle of the 19th century.
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She is known for her independent films and documentaries, including one about Alexander Graham Bell.
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