PSYCHIC EXCITATION OF GASTRIC GLANDS APPETITE. 7:5 



actually reached their mouths, and patiently waiting till the food is 

 given them. Hence for success in the experiment, eager, impression- 

 able and excitable animals are necessary. Fourthly, one has to reckon 

 with the sense and cunning of the dog, a factor which is not lightly to 

 be disregarded. Often the animals perceive at once that they are only 

 being teased with the food, become annoyed thereat, and turn away 

 offended at what is being done before them. We must, therefore, so 

 arrange matters as if the animals were not going to be disappointed but 

 fed in reality. If attention be paid to these conditions the experiment 

 of " psychic excitation of the gastric secretion," as we usually term it, 

 will be found to be as reliable as the expciiment of sham feeding. 

 When one is occupied for a length of time with the study of the gastric 

 secretion under different conditions, one becomes convinced of what a 

 dangerous source of error this psychic excitability may become in the 

 different experiments. W T e must constantly fight, so to speak, against 

 this factor, keep it ever in view and guai^d against it. If the dog 

 has not eaten for a long time, every movement, the going out of the 

 room, the appearance of the attendant who ordinarily feeds the animal 

 in a word, every little triviality may give ri?e to excitation of the 

 gastric glands. The minutest attention is necessary in order to avoid 

 such sources of error, and we should not be far wrong if we said that 

 much which has been ascribed in former investigations to the effect of 

 this or that agency, was in reality a result of unobserved psychic 

 influence. Consequently, in order to verify our own conclusions con- 

 cerning the effects of this or that condition, we have performed many 

 of our experiments on sleeping animals, having beforehand convinced 

 ourselves by frequent repetition, that sleep exercises no restraining 

 influence on the working of the gastric glands. 



When we recall to mind the failure of our attempts to obtain a secre- 

 tion of gastric juice by any stimulation whatever of the buccal mucous 

 membrane, and at the same time see how constant and intense the action 

 of this psychic impression is, we are forced to the inevitable conclusion, 

 that in our sham feeding experiment the whole secretory effect is due 

 to the psychic stimulus, that is to say, to the keen desire on the part of 

 the animal for food and the satisfaction of enjoying it. 



In view of the importance of the act of eating, which even now is 

 apparent, but which will become still more obvious when the succeeding 

 periods of secretion are investigated, we have spared neither time nor 

 trouble to arrive at a correct explanation of the mechanism of this 

 factor. We have, therefore, taken in hand a number of modifications of 

 the sham feeding experiment, and these investigations have confirmed 

 the opinion at which we had arrived. If, for instance, the dog has 

 been prepared by a long fast of two to three days, a very intense secre- 



