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 theinterval observed inPawlow's experiments 
was presumably due to a certain amount of injury to the nervous 
connections. If indigestible Bubstances were Bwallowed, 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 - 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 Vie normally formed in the stomach, and, 
1 "Ueber die Function des Hagens," Verliandl. d. Cong. /'. innere Med., Wiesbaden, 
1893. 
- Inaug. Diss., St. Petersburg, 1894. Reported in Jahresb. ii. d. Fortsehr. d. Thicr- 
Chem., Wiesbaden, Bd. xxv. 
