"Alexis St Martin was one of the 19th century’s most important scientific guinea pigs. In 1822, the illiterate young French-Canadian was working as a ‘voyageur’ for John Jacob Astor’s fur-trading company in northern Michigan. He was hanging out with a bunch of rowdies in the company store when a shotgun accidentally went off and he was hit below his left nipple. The injury was serious and likely to be fatal – his half-digested breakfast was pouring out of the wound from his perforated stomach, along with bits of the stomach itself – but a US army surgeon called William Beaumont was nevertheless sent for. Beaumont was pessimistic, but he cleaned the wound as best he could and was amazed the next day to find his patient still alive. It was touch and go for almost a year: St Martin survived, though with a gastric fistula about two and a half inches in circumference. It was now possible for Beaumont to peer into St Martin’s stomach, to insert his forefinger into it, to introduce muslin bags containing bits of food and to retrieve them whenever he wanted."

(here)