66 PHYSIOLOGY OF ALIMENTATION. 



The function of this secretion is, so far as known, purely 

 mechanical, in that it serves to lubricate the bolus of food as 

 it passes through this tube. 



2. The Gastric Juice is the term applied to the secretion 

 of the mucosa of the stomach. Absolutely pure gastric juice 

 can be obtained from human beings only in small quan- 

 tities, impure juice in somewhat larger quantities. Pure 

 juice has been obtained in cases of gastric fistula. Most ob- 

 servations are based upon a study of the impure juice ob- 

 tained by feeding meals of known composition and then 

 evacuating the contents through a stomach-tube or a fistula 

 if such exists. 



Pure gastric juice is best obtained from the dog by the 

 method of "sham feeding " of PAWLOW and SCHUMOW-SIMAN- 

 owsKY. 1 This consists in feeding a dog in which the oesoph- 

 agus has been separated in such a way from the stomacfr 

 that the food never really enters the stomach. When such 

 sham feeding is carried out, a reflex secretion of pure gastric 

 juice occurs. Such a sham feeding may be kept up without 

 injury to the dog for an hour daily, in the course of which 

 time 200 to 300 c.c. of juice may be collected. The quantity 

 secreted in twenty-four hours is subject to great variations, 

 but amounts to about 1/15 to 1/10 the body weight in dogs. 

 If we assume that the same proportion exists between the 

 amount of the gastric juice and the body weight in the case 

 cf the human being, a man weighing 70 kilos would secrete 

 4 to 7 liters daily. 



KONOWALOFF 2 describes the gastric juice obtained from the 

 dog by sham feeding as a clear, colorless, odorless liquid of a 

 specific gravity averaging 1.00478. The acidity given by 

 KONOWALOFF is higher than that of any other author, 0.544 

 percent of hydrochloric acid. A figure approximating this 



1 See Chapter XI, Part 1. PAWLOW and SCHUMOW-SIMANOWSKY; 

 Centralbl. f. Physiol., 1889, III, p. 113. PAWLOW: Work of the 

 Digestive Glands. Trans, by THOMPSON, London, 1903, p. 12. 



2 PAWLOW : 1. c. 



