SECTION VII 
THE ALIMENTARY TRACT. PART 1.— PHARYNX, 
ESOPHAGUS, STOMACH AND INTESTINES 
The portion of the anatomy that we now approach 
varies in construction almost as much through the animal 
kingdom as do the external shape and covering of the 
various orders and much more than do the other systems. 
The reason for this is ob\'ious, an arrangement accommo- 
dative to the differing food chiefly, but not a little to the 
ease ^^dtll which animals obtain and assimilate their nutri- 
ment. It would be impracticable to describe all the varia- 
tions of the orders discussed in this study, but since 
certain gross and minute differences are of importance in 
comparative pathology they wdll be discussed at the ap- 
propriate places. It is my purpose to present in a 
subsequent section a discussion of food in captivity from 
the standpoint of its quality and quantity in relation 
to pathology. 
Doubtless the quality of food is the largest factor in 
the production of disease both of the alimentary tract and 
elsewhere, but I am not at all sure that the quantity may 
not be equally important, in certain groups at least. Thus, 
for example, the ungulate has nearly always available in 
bedding a substance that he can and mil eat, and the 
prevalent idea that an animal will eat only as much as is 
good for him seems not to hold at all times, since over- 
filled rumens are only too common. It might be thought, 
however, that captivity creates a sort of pica, or that 
enforced idleness is conducive to gorging. The use a few 
lines above of the word ''doubtless" may have arrested 
the attention of some, yet when the whole subject is 
reviewed it seems entirely justified. Plimmer puts incor- 
rect food at the head of the list of the causes of enteritis, 
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