66 INTERNAL SECRETION 



membrane, but not the fundus mucous membrane. Atropine 

 does not diminish the reaction of an animal to this excitant. 

 The substance is not a ferment, as boiling an extract leads to an 

 increase rather than a diminution of its properties. 



From these experiments it would seem that we are justified 

 in concluding that the first products of digestion act on the 

 pyloric mucous membrane, and produce in this membrane a 

 substance which is absorbed into the blood-stream and carried 

 to all the glands of the stomach, where it acts as a specific 

 excitant of their secretory activity. This substance may be 

 called the gastric secretin, or gastric hormone. It exists in 

 the mucous membrane in the form of a precursor (progasfrine) 

 which is activated by the boiling water or the hydrochloric 

 acid. 



In the normal secretion of gastric juice there is a nervous 

 secretion due to the secretory fibres in the vagus, and a chemical 

 secretion due to the chemical stimulation of the secretogogues 

 or of the hormones produced by them. 



The investigations carried out in Pavlov's laboratory seem 

 to indicate that the quantity as well as the properties of the 

 secretion vary with the character of the food. 



Many physicians believe that preparations of the gastric 

 mucous membrane have a therapeutic influence, probably due 

 to their hormone content. Some of these extracts are employed 

 in place of pepsin. 



