GASTRIC SECRETION AND DIGESTION 83 



stomach of the dog into two parts without robbing either 

 of its connection with the circulatory and nervous systems. 

 When the dog has recovered from the immediate effects 

 it may be said to have two stomachs. Either or both may 

 communicate with the exterior by a fistula, while one still 

 retains its normal relations with the esophagus and small 

 intestine. This arrangement makes it possible to place 

 food in one stomach and to obtain and measure the un- 

 mixed juice secreted into the other. The evidence goes 

 to show that when the glands in the lining of one sac are 

 active there is corresponding activity on the part of those 

 in the other. 



A most significant fact is at once noted when such a dog 

 is under observation. There are kinds of food, perfectly 

 appropriate for the animal's nutrition, which may lie in 

 the stomach without exciting any flow of the juice. This 

 is said to be true of bread, white of egg, starch, and some 

 sugars. The same articles of diet would be met by an 

 abundant gastric secretion if they had been eaten with 

 enjoyment by the hungry dog. It makes a radical differ- 

 ence, then, whether these materials enter the stomach 

 through the mouth and attract the favorable notice of 

 the animal, or whether they are slipped through a fistula, 

 a proceeding which would probably not be recognized by 

 him as a mode of feeding. 



On the other hand, there are some things which do cause 

 an outbreak of gastric juice by their mere presence in the 

 stomach and in the absence of any psychic factor. To a 

 somewhat limited extent this is the case with water, 

 though only, it appears, when there is enough of it to dis- 

 tend the stomach slightly. The best-known excitant of 

 the secretion is meat, and the property is said to belong to 

 the extractives or minor substances in this food, and not to 

 the proteins of which it is chiefly composed. Meat causes 

 a considerable flow of the juice, but there is a much longer 

 initial delay than when the psychic element has its normal 

 place. In fact, the total quantity produced when meat is 

 introduced into a dog's stomach without attracting his 



