Began series of experiments to observe little animals in spice infusions

April 24, 1676

Began series of infusions of pepper and other spices in which, over the following five months, he observed microbes. His letter of October 9 chronicled 145 separate observations, ending on September 19. The Lens on Leeuwenhoek page about that letter (see left sidebar) has a chronology of the observations.

This first observation, Pepper 1, involved 3 oz of whole pepper that had been steeping in snow water for 3 weeks. It was full of little creatures.