40 ZOOLOGY. 



the purely carnivorous animals it is shorter, and in the 

 strictly herbivorous, longer than in man, who is generally 

 considered to be omnivorous. Thus, in the lion, it is only 

 thrice the length of the body, whilst in the ram it measures 

 twenty- seven times the length of the animal. The reason 

 assigned is the facility, on the one hand, with which animal 

 substances are digested, and the comparative slowness with 

 which vegetable substances undergo this change. 



Lodged in the abdomen, the intestines are enveloped and 

 supported by a membrane called the peritoneum ; they are 

 further subdivided into the small and large intestines, and 

 these names are preserved, though occasionally inapplicable 

 to the organs described. 



The small intestine follows the stomach immediately, and 

 it is in it that the digestion is completed. It forms about 

 three-fourths of the entire length of the tract of the intestines. 

 The smoothness of its external surface is due to its peritoneal 

 covering ; internally, its mucous membrane presents on its 

 surface a number of villosities and of small follicles. Many 

 transverse folds exist, projecting into the interior of the tube: 

 they are supposed to assist in retarding the progress of the 

 alimentary mass, and thus effecting a more complete absorp- 

 tion of the chyle. The villosities are considered as the means 

 by which this absorption is effected. 



Anatomists divide the small intestine into duodenum, 

 jejunum, ileum a division of but little importance in phy- 

 siology. 



68. Liver and Pancreas. The alimentary matters 

 which have passed into the small intestine mingle with the 

 fluids secreted by its walls and with two peculiar liquids 

 secreted by the liver and pancreas (the bile and the pancreatic 

 juice), two glandular organs situated in the immediate neigh- 

 bourhood of the intestine. 



The liver (Fig. 32), the organ which secretes the bile, is 

 the largest viscus in the body. It is situated in the upper 

 part of the abdomen, mostly on the right side, and extends as 

 far as the lower edge of the ribs. Its upper surface is convex, 

 the lower concave and irregular ; its colour red-brown ; its 

 substance soft, yet compact; and when torn it appears to 

 be formed of an agglomeration of small solid granulations, in 

 which bloodvessels abound and from which arise the excre- 

 tory canals of the bile. 



These excretory canals unite so as to form smaller and 



