774 



PHYSIOLOGY 



is excited by the presence of food in the mouth. This method does 

 not, however, enable us to determine whether the character of the 

 juice will be altered in any way by the changes which the food under- 

 goes in the stomach itself. In order to form an idea of the normal 

 course of secretion of gastric juice, when food is taken into the stomach 

 in the ordinary way, Pawlow has devised another procedure. A 

 small diverticulum representing about one-tenth of the whole stomach 

 is made at the cardiac or pyloric end, in direct muscular and nervous 

 continuity with the rest of the stomach, but shut off from the main 

 part of the viscus by a diaphragm of mucous membrane. The method 

 in which this operation is carried out will be evident by reference 

 to the diagram (Fig. 334). In a dog treated in this way it is found 

 that the amount of juice secreted by the small stomach always bears 

 the same ratio to the amount secreted by the large stomach, while 

 the digestive power of the juice obtained from the small stomach is 

 equal to that obtained from the large. This is shown in the following 

 Table : * 



SECRETION FROM CTASTRIC FISTULA AFTER SHAM MEAL 



In this case a fistulous opening had been established into the 

 large stomach, so that the juice could be obtained simultaneously 

 from both sections of this organ. Secretion was excited by a sham 

 meal, in which the food taken by the animal dropped out of an opening 

 in the neck, and was not allowed to reach the stomach. It will be 

 seen that the secretions in the two sections of the stomach run parallel 

 to one another, while there is an almost exact equivalence between 

 the strengths of the juices obtained from each section. We may 

 therefore regard the secretion obtained from the small stomach as 

 a sample of that produced by the large, and from the changes in 

 this small stomach judge of the effects occurring in the whole organ. 



* Pawlow, " The Work of the Digestive Glands " (translated by W. H 

 Thompson, M.D.), p. 80. 



t The strength of the juice was determined by measuring the number of 

 millimetres of coagulated egg-white (in Mett's tubes) which were digested in 

 eight hours. 



