THE GASTKIC JUICE AND STOMACH DIGESTION. 157 



animals. The simplest and most effectual mode of establishing a gas- 

 tric fistula in the dog is the following : A longitudinal incision, about 

 six centimetres in length, is made through the abdominal parietes in the 

 median line, over the great curvature of the stomach. The anterior wall 

 of the organ is then to be seized with a pair of hooked forceps, drawn 

 out at the external wound, and opened with the point of a bistoury. A 

 short silver canula from one to two centimetres in diameter, armed at 

 each extremity with a narrow projecting rim or flange, is inserted into 

 the wound in the stomach, the edges of which are fastened round the 

 tube with a ligature in order to prevent the escape of the gastric fluids 

 into the peritoneal cavity. The stomach is then returned to its place in 

 the abdomen, and the canula allowed to remain with its external flange 

 resting upon the edges of the wound in the abdominal integuments, 

 which are to be drawn together by sutures. The animal may be kept 

 perfectly quiet, during the operation, by the administration of ether 

 or chloroform. In a few days the ligatures come away, the wounded 

 peritoneal surfaces unite with each other, and the canula is retained in 

 a permanent gastric fistula ; being prevented by its flaring extremities 

 both from falling out of the abdomen and from being accidentally 

 pushed into the stomach. It is closed externally by a cork, which may 

 be withdrawn at pleasure, and the contents of the stomach thus obtained 

 for examination. 



Experiments conducted in this manner confirm, in the main, the results 

 obtained by Dr. Beaumont. Their results are even, in some respects, 

 more satisfactory than those obtained from the human subject ; since 

 animals are more completely under the control of the experimenter, and 

 all sources of deception or mistake are thereby avoided, while the inves- 

 tigation is, at the same time, facilitated by the simple character of the 

 food administered. 



The gastric juice obtained by this method is a clear, colorless, or 

 faintly amber-colored fluid, of a perfectly watery consistency and a dis- 

 tinctly acid reaction. Its specific gravity does not vary much from 

 1010. It becomes slightly opalescent on boiling. 



The following is the composition of the gastric juice of the dog, 

 based upon a comparison of various analyses by Lehmann, Blondlot, 

 Otto, Bidder and Schmidt. 



COMPOSITION OF GASTRIC JUICE. 



Water .......... 975.00 



Free acid 4.78 



Pepsine 15.00 



Sodium chloride 1.70 



Potassium " 1.08 



Calcium " 0.20 



Ammonium "........ 0.65 



Lime phosphate 1.48 



Magnesium "........ 0.06 



Iron " 0.05 



1000 00 



