Who completed blood and urine tests with Pasteur on 20 April 1862?

Claude Bernard completed blood and urine tests with Pasteur on 20 April 1862.

The experiment brought together Pasteur, a chemist studying microorganisms and fermentation, and Claude Bernard, a pioneering physiologist. Their work examined blood and urine during a period when Pasteur was investigating whether microscopic life could arise spontaneously or came from contamination.

The date is one of the precise milestones recorded in accounts of Pasteur’s research. It belongs to the same broader period as his experiments challenging spontaneous generation. Pasteur’s work with sterilized liquids, sealed vessels, and contaminated air helped establish that microorganisms came from existing sources rather than appearing from nonliving matter.

This collaboration is easy to confuse with Pasteur’s later work with assistants such as Charles Chamberland and Émile Roux. Chamberland and Roux became especially important in Pasteur’s vaccine research, while Claude Bernard is the collaborator associated with the 20 April 1862 blood-and-urine tests.