Christiaan Huygens began second series of observations of microbes replicating and expanding on Leeuwenhoek's

Fourteen years after he first replicated Leeuwenhoek's observations of microbes in rainwater infused with pepper, ginger, and coffee, Huygens again replicated and expanded on Leeuwenhoek's observations. As with the first series in 1678, Huygens provided sketches to help the readers visualize what he had seen.

The last record of his observations is dated 25 October.

Five days before that, Huygens wrote to Leeuwenhoek his ideas about spontaneous generation based on his observations.