How did Claude Bernard’s observations of rabbits lead to research on digestion?

Claude Bernard’s research into digestion was sparked by a chance observation in 1846 regarding the urine of rabbits. He noticed that some rabbits were passing clear urine, a trait typically associated with meat-eating animals rather than herbivores. Bernard hypothesized that these rabbits had not been fed and were subsisting on their own tissues.

To test this, he fed meat to the famished animals and subsequently performed an autopsy. This investigation led to the discovery of the pancreas’s critical role in digestion: he found that pancreatic secretions break down fat molecules into fatty acids and glycerin. Furthermore, his experiments allowed him to demonstrate that the primary processes of digestion occur in the small intestine, rather than in the stomach as previously believed.1