Scientific Proceedings. 



73 



absence of free hydrochloric acid. He insists, further, that free 

 HCl is lacking with all foodstuffs throughout the progress of gas- 

 tric digestion in these animals. The total acidity is reported to 

 reach high values in meat digestion and lower figures with other 

 dietaries ; but in each instance it is referable to combined acid. 

 The ability of the dog's stomach to secrete a juice rich in free HCl 

 is not questioned. In the case of this animal, however, Muller 

 believes that the production of acid is limited by the demands of 

 the digesting materials. As soon as the proteins present, or their 

 cleavage products, are combined with acid, the further secretion of 

 the latter ceases. The same behavior is said to characterize the 

 gastric digestion of the cat ; not, however, that of rabbits. Clinical 

 experience further teaches that this description certainly does not 

 apply to the digestive processes in the human stomach, where free 

 HCl regularly occurs in a concentration of 1-2 per mille within a 

 comparatively short period after a test meal. 



These facts and ideas presented by Muller in respect to the 

 chemical and secretory phenomena of gastric digestion in the dog 

 were somewhat surprising to me in view of the experience gained 

 in our laboratory, 1 on animals with gastric fistulas. In numerous 

 experiments on two large dogs we uniformly found the acidity of 

 the stomach contents to increase after a test meal of meat, until 

 free HCl was present in not inconsiderable concentration. An 

 illustrative protocol is reproduced here : 



9-3° 5° grams meat-f- 100 c.c. water fed. 



Analysis of gastric contents ; acidity expressed as HCl. 



Total acidity Free HCl. 



i i 



10.00 0.299 0.090 



10.30 0.475 0.122 



11.00 0.518 0.173 



11. 15 0.497 0.241 



n.35 0.494 0.202 



n.50 0.479 0.195 



12.10 0.382 0.187 



12.30 Stomach empty ; end of gastric digestion. Period of digestion, 

 3 hours. 



Muller calls attention to the difficulty of obtaining gastric 

 contents from dogs through a stomach tube, owing to the fact that 



1 Chittenden, Mendel and Jackson : American Journal of Physiology, 1898, i, 193 ; 

 also "Bicentennial Studies in Physiological Chemistry," Yale University, 1901, 105. 



