GASTRIC JUICE IN THE HORSE. 53 



The salts found in mares' milk namely, chlorides and 

 phosphates of the alkaline and earthy bases are such as are 

 required for the due maintenance of the blood and the animal 

 solids. 



The excrement of the foal appears to contain a good deal of 

 undigested casein e, some fatty matters, doubtless derived from 

 the milk, and substances derived from the biliary secretion 

 of the liver. 



The milk in the colt passes into the stomach most probably 

 with but little admixture of the fluids of the mouth and gullet. 

 The first change which it undergoes is that of coagulation, a 

 change which invariably takes place on milk in the healthy 

 stomach of animals throughout life. The coagulation of milk 

 in the stomachs of animals must be regarded as a special effect 

 of the peculiar secretion of the stomach commonly known as 

 the gastric juice. What is commonly called rennet is the 

 fourth stomach of the calf salted and dried. The solution of a 

 small portion of this substance freely coagulates milk. It was 

 taught a few years ago that the sugar of the milk was con- 

 verted into lactic acid by the rennet, and therefore that the 

 real agent in the coagulation of the milk was the lactic acid. 

 This, however, has been disproved, and no explanation of the 

 effect has as yet been discovered. 



Gastric Juice. The gastric juice, which is the secretion of 

 the inner coat of the stomach after food has been received into 

 its cavity, is an acid fluid, containing a peculiar albuminoid 

 substance, to which the name of pepsine has been applied. 

 An artificial gastric juice may be prepared by heating moder- 

 ately for some time a portion of the mucous membrane of 

 the stomach with a very dilute solution of hydrochloric acid. 

 Such a solution, if kept at a temperature of 1 00 F., will in 

 the course of six or eight hours dissolve muscular fibre, boiled 

 eggs, and albuminoid substances generally. The solutions so 



