490 



THE DIGESTIVE APPARATUS IN MAMMALIA. 



ileum occupies the posterior bonlir of the mesentery, reaching the caecum by keeping on the 



right of the colon ; its insertion is oblique. 



Among the peculiarities of the small intestine, may be cited the presence of an immense 



Peyerian gland, which occupies the latter portion of the canal, where it figures as a band 



measuring from 5 to 65 feet in length. 



The csecum is directed backwards, and shows, on its internal surface, some Peyerian 



patches ; it is sacculated, as in the 

 Fig. 290. Horse, and is furnished with three 



longitudinal bands. The colon is 

 not comi)ri8ed between the layers 

 of the mesentery, except in its 

 latter portion ; for tlie remainder of 

 its extent it is on the left side of 

 the mesenteric layer, where it 

 forms a distinct mass. It describes 

 three turns from right to left, and 

 three turns from left to right; it 

 then pa.sse8 forward, and, crossing 

 again from right to left, insinuates 

 itself between the duodenum and 

 pancreas. It has two of these 

 muscular bands in 11 portion of its 

 track, and even three towards the 

 csecum. 



The rectum is situated above 

 the convolutions of the colon, at 

 the border of a special mesenteric 

 layer. 



4. The Intestines of Carnivora 

 (Figs. 290, 291). 



The intestines of the Carnivora 

 are remarkable foi- their shortness 

 and small volume. In a Dog of 

 ordinary size, they scarcely measure 

 more than HIeetin length, of whicli 

 only from 24 to 28 iiiolies are for 

 the large intestine. In tlie Cat, 

 the latter is about one-half this 

 length, and the entire extent of the 

 viscus is equal to about 6 or 7 feet. 

 With regard tocapacity, Colin gives 

 the following averages : for the 

 Dog's small intestine, 1 quart ; that 

 of the Cat, | of a pint ; for the 

 large intestine in the Dog, nearly 

 1 quart, and in the Cat, a trifle more 

 than \ of a pint. 



The small intestine, suspended 

 at the extremity of a mesentery 

 similar lo that of Solipeds, rests 

 on the inferior abdominal wall. It 

 is distinguished by tlie thickness 

 of its parietes, the length and 

 number of its \\\\\, which cover its 

 inner surface, and which are even 

 found accumulated on Peyer's 



patches. These latter number about 20 in the Dog, and 5 or 6 in the Cat. 



The asecum forms only a small, spirally twisted appendix, lined by a plicated and very 



follicular mucous membrane, particularly in the Cat, and shows at the bottom of the cul-de-sac 



a true Peyer's gland. 



INTESTINES OF THE DOG. 



a. Stomach ; b, duodenum ; c, jejunum ; d, ileum ; e, caecum ; 

 /, ascending colon; g, transverse colon; h, origin of de- 

 scending colon ; (, gre.at omentum ; k, spleen ; I, mesentery : 

 m, pancreas. I, Aorta; 2, great mesenteric artery; 3, 

 artery of the duodenum ; 4, artery of the large intestine ; 

 5, small mesenteric artery. 



