THE RELATION OF DIET TO DISEASE 417 
Relation of Food to Alimentary Tract. 
Food derived from animal sources is high in protein, 
readily digested, and highly putrefactive. This type of 
diet is suited to an alimentary tract wliicli permits rapid 
passage through its length, and is fitted with sturdy walls. 
The gastric section is simple, the intestine short and 
narrow with ill-defined separation of its; parts into small 
gut, cecum and colon. This type is found in all land 
Carnivora. The fish-eating carnivores have a strong 
tubular stomach and an enormous length of intestine, but 
no cecum. The omnivores occupy a middle place. In 
them the alimentary tract consists of a simple stomach, a 
short wide intestinal tube, and a more complex, although 
still comparatively simple, cecum which is generally 
longer than that found in the carnivores. This tract is 
too small to manipulate the bulky vegetable masses neces- 
sary to provide their minimum protein requirement, and 
too long and complicated to dispose quickly of the putre- 
factive animal tissue. Among these animals colitis is 
common, due to the fact that the shape and position of this 
part of the tract favors stasis, or at least a sluggish 
movement of its contents at a point in the digestive 
scheme where the food residue is rich in protein by- 
products, ready for bacterial growth. 
The herbivores with food derived from plants which 
requires a long period of time for its digestion, have, on 
the other hand, voluminous stomachs, or large ceca or 
both; and very long small intestine. In this tract the 
concentrated food of the carnivores would pro\^de an 
enormously excessive protein intake or if only the protein 
requirement is supplied would leave the tract so empty 
that it would be unable to functionate. 
All studies in comparative anatomy demonstrate the 
fact that while neither a complex stomach nor a large 
cecum is essential to the digestion of vegetable food, a 
capacious and complex alimentary canal, as a whole, bears 
a relation to vegetable diet, particularly in the mammals. 
