930 THE EXTERNAL SECRETIONS 



the method of sham-feeding.^ Having established a gastric fistula, 

 the esophagus is divided in the neck and its two cut ends securely 

 fastened to the edges of the wound. The animals so changed soon 

 accommodate themselves to their new conditions and can then be sub- 

 jected to: 



(a) Actual feeding through the distal orifice of esophagus. 



(6) Sham-feeding, by allowing them to masticate the food in the 

 usual way, although it again reaches the outside through the opening 

 in the neck. 



(c) Psychical feeding, in which the animal is merely allowed 

 to see or to smell the food without actually ingesting it. 



The importance of the psychical element in the formation of gas- 

 tric juice may be proved in various ways.^ Thus, it suffices to allow 

 the hungry animal to see the food ; moreover, the secretion then ob- 

 tained is usually more copious than if secreted without the help of 

 psychic impressions. For example, if two dogs are fed weighed amounts 

 of meat through fistulas, without their knowledge, a certain quantity 

 of gastric juice will be secreted by each, but if one of these animals is 

 now given a sham meal of meat, the amount of protein digested by it 

 in a given period of time will be five times greater than that digested 

 by the other animal not psychically stimulated. Those investigators 

 who have studied the effects of gastric fistulae in hum^n beings, have 

 made similar observations and maintain that the seeing, smelling and 

 thinking of palatable food, as well as the leisurely mastication of sapid 

 substances, give rise to a copious flow of gastric juice. Appetite 

 is a potent factor in this process and so is the quality of the food. Food 

 and condiments which the individual liked especially, were more 

 effective than, say, butter, bread and meat. This fact may serve as 

 a reason for the ingestion of a palatable dessert, salad, or fruit at the 

 end of a meal. The purpose of these ''appetizers" is to augment and 

 to prolong the appetite secretion of gastric juice. ^ 



The fact to be deduced from these experiments is that the different 

 kinds of food possess an almost specific stimulating power which en- 

 ables them to vary not only the quantity of the gastric juice, but also 

 the length of the period intervening between their ingestion and the 

 appearance of the secretion. In the case of saliva it is easily observed 

 that this latent period is short, a fact which is in keeping with func- 

 tional requirements. Evidently, since the food enters the mouth 

 quickly and remains here for only a relatively short period, it is 

 essential that this secretion be produced in the shortest possible 

 time. In the case of gastric juice an urgency of this kind does not 

 exist and hence, the latent period may be appreciably prolonged. 



1 Pawlow and Schumowa-Simanowskaja, Zentralbl. fiir Physiol., iii, 1889. 



2 Bogen, Pfltiger's Archiv, cxvii, 1907. 



3 Rabinowitch, Dissertation, Giessen, 1907 (spices); Pinkussohn, Miinch. med. 

 Wochenschr., 1906 (coffee and cocoa) ; Kast, Archiv fiir Verdauungskr., xii (alcohol) ; 

 Bickel, Berhner klin. Wochenschr., 1906 (mineral waters). 



