TEXT-BOOK OF PHYSIOLOGY 



been established in both carnivorous and herbivorous animals with a view 

 of studying the process as it takes place in them. The results obtained in 

 these instances in many respects corroborate those obtained by Dr. Beau- 

 mont, though many new facts, unobserved by him, have been brought to 

 light. 



Much additional information as to the mode of secretion and the char- 

 acteristics of the gastric juice has been obtained, since the introduction of two 

 new procedures by Pavlov. The first consists in establishing a gastric 

 fistula and subsequently dividing the esophagus in the neck, and then so 

 adjusting the divided ends that they heal separately into an angle of the skin 

 incision. The second procedure consists in forming a diverticulum or pouch 

 out of the cardiac end of the stomach which opens on the surface of the ab- 

 domen but is separated from the rest of the stomach by a thin septum formed 

 of two layers 'of mucous membrane. (Fig. 73.) The serous and muscle-coats 

 of this pouch are in direct continuity with the large stomach and all possess 



the same vascular and nerve connections. 

 Because of this fact this miniature stomach, 

 about one-tenth the size of the natural 

 stomach, exhibits the same phenomena, so 

 far as the secretion of the gastric juice is con- 

 cerned, as the large stomach does. The phe- 

 nomena which are observed in it may be 

 taken as an indication as to the phenomena 

 which are taking place in the natural stomach. 

 By the first procedure it is possible to feed 

 an animal with different kinds of food and to 

 observe the effects of psychic states on the 

 secretion of gastric juice. As the swallowed 

 food is discharged from the lower end of the 

 STOMACH TO THE MINIATURE divided esophagus the appetite continues, and 



CT xS'tt hence the animal wil1 eat f r several hours ' 

 BY PAVLOV. V. The natural By the second procedure it IS possible to col- 

 miniature lect gastric juice from the miniature stomach 

 and to study the effects on its quantity and 

 quality produced by psychic states, mastica- 

 tion, different articles of food, and by the 

 process of digestion itself as it goes on in the large stomach. In both in- 

 stances the juice is obtained free from admixture with saliva or food. 



Gastric Juice. The gastric juice obtained from the human stomach 

 free from mucus and other impurities is a clear, colorless fluid with a con- 

 stant acid reaction, a slightly saline and acid taste, and a specific gravity 

 varying from 1.002 to 1.005. The juice obtained from the dog's stomach 

 possesses essentially the same characteristics, though its acidity as well as its 

 specific gravity are slightly greater. When kept from atmospheric influences, 

 it resists putrefactive change for a long period of time, undergoes no apparent 

 change in composition, and loses none of its digestive power. It will also 

 prevent and even arrest putrefactive change in organic matter. The chemic 

 composition of the gastric juice has never been satisfactorily determined, 

 owing to the fact that the secretion as obtained from fistulous openings has 

 not been absolutely normal. It may however be said to consist of water, 



FIG. 73. DIAGRAM SHOWING 

 THE RELATION OF THE NATURAL 



stomach, 

 stomach. 



S. The 

 e, e. The septum 



y t 

 The 



abdominal walls. 



