ALIMENTATION. 185 



Vomiting in the horse is very infrequent and difficult, on ac- 

 count of there being no dilatation of the stomach at the point 

 where the oesophagus enters, the oesophagus being very narrow at 

 its termination and being nearly filled by folds of its mucous mem- 

 brane. 



It takes place by a deep inspiration, forcing the diaphragm down 

 and fixing it; then a relaxation of the cesophageal orifice, with a 

 spasmodic contraction of the abdominal muscles, completes the 

 act. 



THE BILE. 



The bile, secreted by the liver, acts upon the food in the upper 

 part of the small intestine. It is brownish-green in color, alkaline 

 in action, bitter in taste. Its specific gravity is higher than the 

 gastric and lower than the pancreatic juice, and its amount in 24 

 hours is from n to 13^ pounds. 



Its composition is as follows: 



Water. 

 Mucin. 



rri u / Glycocholate of Soda. 

 ts \Taurocholateof Soda. 



Bile coloring matter { 



Cholesterin. 

 Iron and salts. 



The Mucin comes from the biliary passages, not from the liver 

 cells. 



Gmelin's Test for Biliary Pigment. 



Spread a drop of diluted bile on a porcelain plate and add a. 

 drop of yellow nitric acid to it. A play of colors results, green, 

 blue, violet and yellow. (Charles.) 



Pettenkofer's Test for Biliary Acids. 



Add a little sugar to the fluid, then shake and add a few drops 

 of strong sulphuric acid. A beautiful purple or violet coloration 

 will appear. 



Cholesterin is excreted by the liver, and is derived from broken- 

 down nerve-tissue. Under the microscope it appears as delicate, 

 thin, flattened, super-imposed plates, with one corner broken off. 



13 



