From a previous blog post (538: Gut Science Week):

One of the major leaps forward in gut science began with an accidental shooting at a trading post on June 6, 1822. A fur trader named Alexis St. Martin took a bullet in the abdomen, leaving him with a hole ripped through his muscle, bone and internal organs…

His doctor, William Beaumont, could literally tie a bit of food on a string, shove it into St. Martin’s stomach through the hole, and pull it back out again. Using this one weird trick, Beaumont extracted samples of the man’s gastric juices. Over eight years and more than 200 awkwardly invasive experiments, St. Martin and Beaumont gave humanity its first real understanding of how digestion works.