GASTRIC JUICE IN THE OX. 105 



or proper stomach, the other stomachs at that period being in 

 a rudimentary state (p. 98). 



Gastric Juice. The gastric juice in the ox is the secretion 

 from the membrane of the fourth stomach, by which the final 

 effect of stomach-digestion is produced on the aliment. It is 

 the chief agent in the digestion of the albuminoid portions of 

 the food, while it exerts hardly any influence over its starchy 

 and saccharine constituents. When there is no food in the 

 stomach, the fluid present shows quite different qualities from 

 those possessed by the fluid secreted when food has reached the 

 organ. The fluid obtained from the empty stomach has either 

 no effect on litmus-paper or its effect is alkaline ; but after 

 food has passed into the stomach, the secreted fluid is uniformly 

 acid. In this state the gastric juice is a clear colourless liquid, 

 with a peculiar odour, and slightly saline and acid taste. It 

 does not become turbid when boiled, and is distinguished by 

 a remarkable antiseptic property. It has no tendency to be- 

 come putrid, even when kept at the temperature of 100 Fahr. 

 The nature of the acid present in the gastric juice has been 

 much debated. According to some physiologists, it is the 

 hydrochloric acid and this is the prevailing opinion. The 

 most probable case is, however, that it is a mixture of hydro- 

 chloric and lactic acids. Not a few contend that it is lactic 

 acid alone, while others maintain that it is phosphoric acid in 

 the form of superphosphate of lime. Some saline matters have 

 been detected in the gastric juice such as common salt (chlo- 

 ride of sodium), small quantites of chlorides of calcium and of 

 magnesium, lactate of soda, and traces of phosphate of lime 

 and of iron. The amount of phosphate of lime is very small, 

 and the sulphates and phosphates of the alkalies are hardly 

 discoverable. The gastric juice, however, contains, in small 

 proportion, a peculiar organic compound, which has been 

 termed pepsinc. To this substance, aided by the free acid pre- 



