The first to make and use lenses to observe living microorganisms. He constructed simple microscopes capable of magnifying objects 100 to 300 times. He kept his techniques a secret. Developed the technique of pasteurization to kill unwanted organisms.
Phagocytes defend the body against invading microorganisms.
He also cultivated Neisseria gonorrhea. Discovery of intracellular reproduction of tobacco mosaic virus. Did experiments refuting spontaneous generation. Boiled broth infusions containing organic matter and sealed the flasks to demonstrate that no organisms would develop spontaneously in them. He was an italian cleric and scientist.