Digestive System General. 65 



tion, visible externally; sometimes such division existing 

 internally is scarcely visible outside ; in either case the Pyloric 

 end may be itself further sub-divided. Again, though very 

 rarely, there is found a sort of glandular ProventriculuSj 

 separated by a constriction from the wide muscular part of 

 the Stomach. Further, the Stomach may be complex ^ made 

 up of many compartments, and this even in some flesh- eating 

 species. Lastly, the Stomach is sometimes found intesUni-form. 

 The size of the Cardiac portion of the Stomach is mainly 

 dependent on the nature of the food ; it attains its maximum 

 in the herbivorous Ruminantia (in which the first three 

 stomachs are apparently divisions of the * Fundus ventricuK * 

 of Man), and is much reduced in most flesh feeders ; this 

 correlation is further demonstrated by the fact that the 

 fourth Stomach of the Ruminant is the largest as long as 

 the animal sucks. In Mammalia a capacious and complex 

 alimentary canal, as a whole, is almost invariably correlated 

 with a restricted vegetable diet ; though the extent to which, 

 and the mode by which the complexity is attained is variable : 

 either a highly developed and concentrated glandular appa- 

 ratus may be added to the Stomach, as in Castor, Myoxus, 

 and Phascolomys ; or the Stomach itself may be amplified, 

 subdivided, or sacculated, as in the Ruminantia, and Her- 

 bivorous Marsupialia ; or both these complexities may be 

 combined, as in the existing Sirenia and the Bradypodidae ; 

 or, lastly, if a simple condition of the Stomach is retained, 

 the compensation of complexity may be attained by the pre- 

 sence of a large sacculated colon and caecum. The Pylorus 

 is occasionally defended by a valve. Accumulation and de- 

 tention of vegetable food in the stomach occasions frequently 

 'bezoar* concretions. 



The relative length of the Intestinal canal varies, being, in 

 general, longest in the vegetable feeders, and short in the flesh 



K 



