396 PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



the reserve store of tissue-albumen, and finally dies practically of starva- 

 tion. If the animals are allowed to lick the wound, and so cause the bile 

 to enter their alimentary canal, the phenomena of impairment of nutri- 

 tion are very much less marked. So, also, if they are fed on double 

 the amount ordinarily required to maintain their nutritive equilibrium, 

 the carbohydrates especially being in excess, the phenomena of mal- 

 nutrition may be largely prevented. In animals where the secretion of 

 bile is prevented entirely from reaching the intestines, we find that obsti- 

 nate constipation is usually added to the symptoms of disturbed nutri- 

 tion, and that the faeces which are occasional^ passed are clay-colored,' 

 with a most offensive putrefactive odor. It would, therefore, appear that 

 the bile, by acting as a stimulus to the mucous membrane of the intestine, 

 tends to maintain the normal peristaltic contractions of this part of the 

 alimentary canal, and to that extent, therefore, acts as a natural purgative, 

 while at the same time it largely prevents putrefaction and decompo- 

 sition. The bile is, however, largely an excretion. Many of its con- 

 stituents are removed unchanged, while some of them are reabsorbed and 

 again enter the blood-current. The mucin and cholesterin pass through 

 with the faeces unchanged. The bile-pigments undergo decomposition in 

 the intestinal tube, and are partly excreted with the faeces under the form 

 of hydro-bilirubin, a characteristic brown coloring-matter of excrement, 

 and are partly eliminated as urobilin by the urine. The bile salts are for 

 the most part reabsorbed by the walls of the upper portion of the small 

 intestine, only a small quantity of glycocholic acid being found in the 

 faeces. The taurocholic acid is largely absorbed, it being previous^, 

 perhaps, decomposed into cholic acid and taurin, the latter being con- 

 stantly absorbed, while part of the cholic acid may perhaps be removed 

 with the faeces. 



II. THE PANCREATIC SECRETION. The pancreatic fluid is poured 

 into the small intestine immediately after the entrance of the bile, 

 or in some instances simultaneously with it and the secretion of 

 B runner's glands. While the pancreas is one of the most constant 

 of all glands, existing in all mammals, birds, reptiles, in most fish and 

 insects, its anatomical form is subject to great variation in different 

 animals. In the dog, as in other mammals, most birds, and reptiles, 

 the pancreas is situated in the concaA r ity of the duodenum. Also in 

 the dog, and in other mammals in w r lrich the duodenal mesentery is 

 short or absent, this gland is thick, elongated, and bilobed, one portion 

 extending horizontally toward the spleen, while the other portion de- 

 scends at a right angle, parallel to the duodenum (Fig. 155). At the 

 angle the pancreas is closely adherent to the duodenum, and often over- 

 laps it, being connected by a multitude of small blood-vessels, while the 

 descending portion lies free in the abdominal cavity. There are in the 



