The chemical mechanism of gastric secretion 1

Preface. The earliest phase in the process of gastric digestion has been shown by Pawlow and his pupils to be chiefly dependent upon a psychic condition resulting in nervous impulses passing by the vagi to the gastric glands and bringing about their activity. This form of secretion is comparatively transitory and the later stages are regarded as due to certain exciting substances, present in the food or formed in the early stages of the digestive process, acting on the peripheral endapparatus of the sensory nerves of the stomach and thereby evoking a reflex secretioni of the juice. Direct stimulation of the glandular mechanism by means of the exciting substances becoming absorbed is thought by Pawlow to be very improbable though difficult to actually disprove. Since the work of Bayliss and Starling, which showed that the pancreas could be caused to secrete without the intervention of any nervous mechanism but simply by the direct exciting effect of something which could be introduced into the general circulation in the process of absorption from the alimentary canal, it has of course been possible that the so-called chemical secretion of the stomach might be explained in a similar manner. Certain substances absorbed in the stomach might in the process of absorption extract from the gastric mucous membrane certain chemical principles which when introduced into the blood stream would finally act as specific excitants of the flow of gastric juice. The problem involved a consideration of (1) what substances, when absorbed, would be most potent in introducing these chemical excitants into the circulation, and (2) what part of the alimentary tract would be the most probable path for the absorbed substances to take. In connection with the first part of the problem it suggested itself