In the 19th Centrury, everal experiments on human digestion were conducted on someone with a gunshot wound that left a fistula providing access to the stomach, somewhat like those cannula: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;William_Beaumont#Experiments_with_St._Martin" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;William_Beaumont#Experiments_w...</a>