BY DR. LAUDER BRUNTON. 475 



** 101. Secretion of Saliva after Decapitation. 



Make a parotid fistula in a rabbit ; decapitate it ; split the 

 head in the middle line by a knife and hammer ; remove the 

 brain from that half of the head on which the fistula has been 

 made, apply a piece of filter-paper colored red by litmus to the 

 orifice of the duct, and irritate the roots of the facial as they 

 enter the internal auditory foramen, either electrically or by 

 touching the nerve with a drop of acid. A blue spot will appear 

 on the paper, showing that saliva has been secreted. 



SECTION II. DIGESTION IN THE STOMACH. 



102. In the stomach the albuminous constituents of the food 

 which were unaffected by the saliva are dissolved by the gas- 

 tric juice, and to a great extent converted into peptones. If 

 the}- were merely dissolved, they could only be absorbed in 

 very minute quantities, for albumin will hardly diffuse through 

 animal membranes. The peptones into which the albuminous 

 substances are converted, on the contrary, diffuse very readily, 

 and are thus easily absorbed. The gelatinous substances in 

 the food are also changed somewhat by the gastric juice, so 

 that after they have been acted on by it they no longer gela- 

 tinize. The transformation of starch into sugar by the saliva, 

 which was begun in the mouth, also goes on in the stomach, 

 the acidity of the gastric juice being too slight to arrest it. 



Unlike saliva, gastric juice cannot be readily obtained from, 

 man or animals, at any rate in a state of purity, without an 

 operation. It is therefore necessary to establish a gastric 

 fistula in a dog in order to collect a sufficient quantity of gas- 

 tric, juice for examination. 



** 103. Establishment of a Gastric Fistula. The 

 object of making a gastric fistula is twofold : 1st, to obtain 

 gastric juice for examination; and, 2d, to observe the process 

 of secretion within the stomach itself. 



The method adopted by Bassow was simply to make an in- 

 cision in the abdominal parietes, to sew the stomach to the 

 edge of the wound, and then to make an opening in the stomach 

 itself. The fistula was plugged with a piece of sponge. It 

 was, however, very liable to close, and was too small to allow 

 the interior of the stomach to be observed. Blondlot pre- 

 vented the wound from closing by placing in it a canula, which 

 was closed with a cork, so that the gastric juice and products 

 of digestion might not be lost during the intervals between 

 his observations. 



This method, as improved by Bernard, is the one usually 

 employed. Bernard's canula consists of two tubes, each of 

 which has at one end a broad flange. One tube screws into 

 the other, so that the distance between the two flanges can he 



