180 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



esis, especially that part connecting the border-cells with the t formation of 

 HC1, can only be accepted provisionally until further investigation confirms 

 or disproves it. It should be stated that the alkalinity of the secretion obtained 

 from the pyloric glands by Heidenhain's method has been attributed by some 

 authors to the abnormal conditions prevailing, especially to the section of the 

 vagus fibres which necessarily results from the operation. Contejean l asserts 

 that the reaction of the pyloric membrane under normal conditions is acid in 

 spite of the absence of border-cells. 



Influence of the Nerves upon the Gastric Secretion. It has been very 

 difficult to obtain direct evidence of the existence of extrinsic secretory nerves 

 to the gastric glands. In the hands of most experimenters, stimulation of the 

 vagi and of the sympathetics has given negative results, and, on the other 

 hand, section of these nerves does not seem to prevent the formation of the 

 gastric secretion. There are on record, however, a number of observations 

 which point to a direct influence of the central nervous system on the secre- 

 tion. Thus Bidder and Schmidt found that in a hungry dog with a gastric 

 fistula (page 225) the mere sight of food caused a flow of gastric juice ; and 

 Richet reports a case of a man in whom the oesophagus was completely oc- 

 cluded and in whom a gastric fistula was established by surgical operation. 

 It was then found that savory foods chewed in the mouth produced a marked 

 flow of gastric juice. There would seem to be no other way of explaining the 

 secretions in these cases except upon the supposition that they were caused by a 

 reflex stimulation of the gastric mucous membrane through the central nervous 

 system. These cases are strongly supported by some recent experimental 

 work on dogs by Pawlow 2 and Schumowa-Simanowskaja. These observers 

 used dogs in which a gastric fistula had been established, and in which, more- 

 over, the oesophagus had been divided in the neck and the upper and lower 

 cut surfaces brought to the skin and sutured so as to make two fistulous 

 openings. In these animals, therefore, food taken into the mouth and subse- 

 quently swallowed escaped to the exterior through the upper cesophageal 

 fistula, without entering the stomach. Nevertheless this " fictitious meal," 

 as the authors designate it, in the case of certain foods (meats), brought about 

 an increased formation of gastric juice, although, curiously enough, other foods, 

 such as milk and soup, gave negative results. If in such animals the two 

 vagi were cut, the " fictitious meal " no longer caused a secretion of the gas- 

 tric juice, and this fact may be considered as showing that the secretion 

 obtained when the vagi were intact was due to a reflex stimulation of the 

 stomach through these nerves. Finally, these observers were able to show 

 that direct stimulation of the vagi under proper conditions causes, after a long 

 latent period (six or seven minutes), a marked secretion of gastric juice. A 

 satisfactory explanation of the unusually long latent period is not given. 



Taking these results together, we must believe that the vagi send secretory 

 fibres to the gastric glands, and that these fibres may be stimulated reflexly 



1 Archives de Physiologic, 1892, p. 554. 



2 Du Bois-Reymontf s Archiv fur Physiologic, 1895, S. 53. 



