GASTRIC DIGESTION. 361 



of animal matter to be introduced into the stomach. The gastric mucous 

 membrane secretes gastric juice throughout its entire extent, and the 

 digestion in the stomach in carnivora is the most important staoe in the 

 preparation of food for absorption. The secretion is rapidly poured out 

 after taking a meal, the activity being in accordance with the degree of 

 stimulation -which the aliments exercise on this viscus. Thus there is 

 less secretion formed when gelatin, gum, starch, and other indigestible 

 substances are swallowed, while the secretion is copious when meat, bone 

 and other albuminous bodies are introduced into the stomach. The total 

 amount of gastric juice secreted by carnivora can only be determined 

 with difficulty. It has been stated as one hundred grammes for each kilo 

 of body weight — an amount which is evidently too large ; probably one- 

 fourth the amount would be nearer the truth. As the gastric juice of 

 the carnivora is obtained with the greatest readiness, it is the secretion 

 which has been most studied. It contains a larger percentage of acid 

 and pepsin than that of omnivorous and herbivorous animals, and in 

 equal time will digest four times as much cooked albumen as the gastric 

 juice of the sheep. It has been stated that a dog is able to digest one- 

 fifth of his own weight at one meal. Nevertheless, the gastric juice does 

 not convert all the food taken into the stomach into peptones ; a large 

 part is merely disintegrated and passes into the small intestine to be 

 acted upon by the pancreatic juice. When excessive amounts of meat 

 are taken, as is occasionally the case in young dogs, it will escape entirely 

 unaltered through the intestines. Considerable time is required for 

 gastric digestion in carnivora. Thus, albumen given to dogs has been 

 found still coagulable by heat after a sojourn of three hours in the 

 stomach, indicating that in a certain portion digestion had not com- 

 menced. Again, coagulated albumen has been found unaltered after a 

 period of four hours ; fibrin has been found swollen and transparent, 

 but not dissolved; while gluten, after having remained four hours in the 

 stomach, has been found almost unaltered. 



Spallanzani states that masses of meat inclosed in tubes were found 

 partially undigested after eleven hours, while Colin claims that at least 

 twelve hours are required for a carnivore to digest the amount of meat 

 which it would take spontaneously at a single meal. Thus, Colin gave 

 to a cat which had fasted for twenty -four hours two hundred grammes of 

 horse-meat, and found that five hours afterward the stomach contained 

 one hundred and fifty grammes of unaltered meat; but forty-five grammes, 

 therefore, or only about one-fourth, having been disintegrated. To another 

 cat two hundred grammes of horse-meat were given after fasting twenty 

 hours, and after twelve hours sixty-four grammes could still be recog- 

 nized. Similar data were also obtained in the case of the dog. It is not 

 astonishing that the food remains so long in the stomach. Time is given 



