76 THE SECRETION OF GASTRIC JUICE. [BOOK II. 



fistula should be performed with antiseptic precautions, and that 

 in collecting the gastric juice some experimenters have found it 

 useful to suspend the animal in a sling, the reader will have been 

 placed in possession of the knowledge required by one about to 

 make an investigation necessitating the establishment of gastric 

 fistula?. 



When a gastric fistula is established in a dog, the juice which 

 flows from it is naturally mixed with saliva. To obviate this admix- 

 ture some experimenters 1 established salivary fistulas, so as to 

 prevent the submaxillary and parotid secretions from entering the 

 stomach. 



SECT. 4. THE MORE OBVIOUS PHENOMENA ATTENDING SECRETION 

 OF THE GASTRIC JUICE. 



The Influence of the Nervous System upon it. 



The fasting In man and many carnivorous animals the process 

 stomach is of gastric digestion is one which, during health, only 

 pale ; it con- OCC upies a few hours. At its completion, the stomach is 

 trie 1 juice aS f un d quite empty, the pallid, uninjected mucous mem- 

 brane being merely covered by a thin layer of mucus, 

 which at the pyloric end usually has an alkaline, and at the cardiac 

 end an acid reaction. There is no accumulation of gastric juice in 

 the resting stomach, such as would occur if the gastric, like certain 

 other glands, secreted continuously. 



The observations made on this subject by Dr Beaumont on the man 

 Alexis St Martin 2 are of far greater value than those made upon dogs 

 with gastric fistulse, for the man in spite of his ; fistula was in a thoroughly 

 physiological condition, whilst a dog with a cannula in situ has ipso facto 

 a constant stimulus acting upon the stomach. It is in this way that we 

 explain the fact that large quantities of gastric juice have been found in 

 the stomach of a dog with 'gastric fistula, though it had been fasting for 

 24 hours 3 , and that some observers 4 , drawing their conclusions merely from 

 the case of dogs with gastric fistulse, have asserted that the secretion of 

 gastric juice like that of bile is a continuous one. 



From the fact that during fasting the stomach does not contain 

 gastric juice we should conclude that the saliva, which unquestionably 

 is constantly being swallowed and passing into the stomach, is only 

 capable, on reaching the gastric mucous membrane, of causing the 



1 Bardeleben, and Bidder and Schmidt. 



2 These observations have been confirmed by the observation of other cases of 

 gastric fistula in man. See Heidenhain, Hermann's Handbuch, Vol. v. p. Ill (foot- 

 note). 



3 Heidenhain, Hermann's Handbuch, Vol. v. (1880), p. 111. 



4 Braun, Eckhard's Beitr. z. Anat. u. Phys., Vol. vn. (1876), p. 29. 



