1. Antonie van LeeuwenhoekLeeuwenhoek was a Dutch microscopist who made most of his contributions while working as a chamberlain in Delft. Although he lacked scientific training, he had a particular passion for grinding lenses into simple microscopes and observing the natural world. The Encyclopedia Britannica lists a number of elements of the microscopic world that Leeuwenhoek was among the first to describe accurately, including spermatozoa, the ridges of muscle tissue, the mouthparts of insects, the fine structures of plants, and globules red. Arguably Leeuwenhoek's most important contributions to science were those that directly challenged the long-standing theory of spontaneous generation. Using his own techniques, the details of which remain a mystery to this day, he was able to discover the truth behind the life cycles of many creatures thought to generate spontaneously from organic matter, such as fleas and attic weevils.2 . Louis PasteurLouis Pasteur was a French chemist born December 27, 1822. Most of his studies took place in Paris, where he received a doctorate in science in 1847. Soon after, he studied recent discoveries in the field of chemistry, an effort that eventually led him to the discovery of molecular asymmetry, paving the way for the field of stereochemistry. This discovery earned him enough attention to be appointed professor of chemistry at the University of Lille, France. While a chemistry professor, Pasteur was approached with the problems of a local distillery, launching the scientist's research into alcoholic fermentation. As he solved the distillery's various problems, he gathered the evidence and knowledge that led him to... middle of paper ...... to conserve the culture. When he returned to the culture to see what had happened, he noticed that the bacteria had apparently been destroyed. This ultimately led him to the discovery of lysozyme, an enzyme naturally found in mucous membranes that can destroy certain types of bacteria. Fleming's most famous discovery, however, was that of penicillin, and again, it happened entirely by chance. Echoing the discovery of lysozyme, the story of penicillin begins with a contaminated bacterial culture, this time by a mold. Again, Fleming allowed the culture to mature and found that the bacteria's growth had been severely inhibited by the presence of the mold, which was later identified as a member of Penicillium. Fleming and his team, however, failed to transform the antibiotic into a useful form, which is why they shared the 1945 Nobel Prize with the researchers who did so..