THE FUNCTIONS OF THE DIGESTIVE ORGANS. 499 



fictitious meal was much more thoroughly digested than the meat in the 

 stomach of the other dog. 1 



It is an old experience that psychic influences may destroy the appetite. 

 In this case there are great individual differences; often slight anger will 

 suffice to destroy the appetite completely. These experiences can be shown 

 experimentally to be well founded. Thus, among others, A. Bickel 2 has 

 found that the gastric secretion stops at once when a dog is confronted 

 with a cat. Undoubtedly the same relations exist in man. Naturally, 

 in the latter case we do not possess such a rich field for observation. In 

 man such experiments are influenced much more by secondary effects than 

 is the case with animals, where reactions take place more in accordance with 

 sensatory impressions. Certain imaginary effects are not so prominent 

 in animals as in man. On the other hand, such experiments carried out 

 with human beings are less valuable, because, when there is a gastric fistula, 

 there is usually some pathological derangement of the stomach or cesopha- 

 gus. Frequently there are tumors, especially cancers, to be considered. 

 The latter are especially likely to cause a most deep-seated effect upon the 

 whole metabolism of the cells and weaken the whole body, so that it is out 

 of the question to speak of a normal function of the lining of the stomach 

 and of its glands, even although the carcinoma may not have attacked 

 the stomach itself. On the other hand, now and then the formation of a 

 gastric fistula becomes necessary when there is no chance for the food to 

 reach the stomach through the oesophagus, for example, as a result of 

 strictures caused by injury to the mucous membrane. In such cases it is 

 possible to carry out observations with human beings which are similar to 

 those of Pawlow with dogs. Thus, Hornborg, 3 who studied a case of gas- 

 tric fistula with oesophageal stricture, observed that it was not possible to 

 detect psychic influences in all cases. The chewing of substances with 

 pleasant taste produced a secretion, while chewing of indifferent or badly 

 tasting substances had no effect. Chewing of itself appeared to act favor- 

 ably upon the gastric secretion, while the mere sight of food had no effect. 

 On the other hand, the secretion stopped if the boy was not allowed to eat 

 at once something that tasted good; this evidently made the boy angry, 

 and this feeling was indicated by a flow of tears. 



The secretion of the gastric juice is produced not merely as a result of a 

 reflex action, but we recognize certain other influences as well, which may 

 be exerted within the stomach itself. Mechanical irritation does not 

 suffice to start the flow of the juice. Chemical influences alone are to be 



1 The highly interesting studies by Pawlow and his students have nearly all appeared 

 in Russian only. His lectures have been translated into German by A. Walther, and 

 published in 1898 by Bergmann of Wiesbaden. 



3 Deut. Med. Wochschr. 31, 1829 (1905). 



3 Inaug. Dissert. Helsingfors (1903). 



