INFLUENCE OF LOCAL STIMULATION. 541 



Heidenhain found that following a latent period of some fifteen minutes 

 after placing food in the organ, the stomach commenced to secrete gastric 

 juice. This delay beyond the interval observed in Pawlow's experiments 

 was presumably due to a certain amount of injury to the nervous 

 connections. If indigestible substances were swallowed, the secretion 

 was much longer delayed. The conclusion which Heidenhain arrived 

 at was that certain products of digestion when absorbed stimulate the 

 flow of gastric juice. The question then arises, What are these products 

 of digestion, and by what paths are they absorbed ? Are the completely 

 digested foodstuffs (that is to say, completely digested as far as gastric 

 digestion is concerned) passed on to the intestine and there absorbed, 

 or are they directly absorbed in the stomach ? 



As regards the change undergone by different proteids when subject 

 to gastric digestion, there is reason to believe that the stage reached 

 in the stomach is not a final one, some further change taking place 

 in the duodenum, and that the amount of peptone formed in the 

 stomach may not be large, the proteose stage being, to a great 

 extent, the final stage of gastric digestion. If this is so, and if 

 the secretion from the gastric mucous membrane is influenced by 

 absorbed peptones, it must be influenced by peptones absorbed in 

 the small intestine. On the other hand, we are unable to state 

 definitely to what extent the intermediate results of the digestion 

 of proteids are absorbed in the stomach. As regards the carbohydrate 

 foodstuffs, v. Mering 1 has shown that sugars are absorbed by the 

 stomach. If it is absorbed digestive products that provoke the 

 secretion, is it a specific product or products that cause this to occur, or 

 is it a common characteristic of all ? Chischin 2 has attempted to 

 answer this question. He finds that feeding a dog (which has had 

 a portion of its stomach isolated after the manner of Pawlow) with 

 different varieties of food, results in very different characters being 

 shown by the secreted juice during the course of digestion, and he 

 hence infers that there must be some specific stimulus or stimuli 

 influencing the secretion. The different substances were administered 

 in such a manner as to avoid the " psychical " influence on the secretion. 

 The administration of distilled water, gastric juice, or simple hydro- 

 chloric acid, caused but little change. Egg-albumin, sugar and starch 

 solution, were tested with the same negative results. The administra- 

 tion of peptone, however, resulted in a pronounced secretion. Chischin 

 considers that peptone was not only able to cause the gastric mucous 

 membrane to become active, but also to sustain it in activity. If egg- 

 albumin be administered so as to evoke the psychical influence, a well- 

 marked and sustained secretion resulted. Chischin accordingly explains 

 the usual process of secretion as occurring in the following manner : At 

 the time of taking food the first flow of gastric juice is determined by 

 the reflex psychical influences involved in taking food. The digested 

 proteids are able later to evoke a secretion, at a time presumably 

 when the psychical influence begins to wane. 



According to these experiments, then, we may assume that small 

 quantities of peptone may be normally formed in the stomach, and, 



1 "Ueber die Function des Magens," Verhandl. d. Cong. f. innere Med., Wiesbaden, 

 1893. 



2 Inaug. Diss., St. Petersburg, 1894. Reported in Jahrcsb. ii. d. Fortschr. d. Thier- 

 Chem., Wiesbaden, Bd. xxv. 



