ACIDITY OF (J AST LUC JUICE. :!1 



tionship is easily to be understood in the light of our explanation. The 

 greater the quantity of juice the more rapidly will it flow over the 

 stomach-wall, and therefore the less will it become neutralised. The 

 acidity observed under these conditions will thus more closely approxi- 

 mate to that which is real and authentic. In order to test this explana- 

 tion, experiments of various kinds were instituted by Dr. Ketscher. Since 

 the wall of the stomach is usually covered with a considerable layer 

 of mucus, it is quite natural that the first poi'tions of juice secreted, for 

 example under the influence of sham feeding, will manifest the lowest 

 acidity. The more freely and rapidly the juice flows, the greater will 

 be its acidity. During the decline of the secretion we find an absence 

 of the low acidity pertaining to a corresponding rate of outflow 

 at the beginning of the experiment. Obviously this is because the 

 stream of juice has been neutralised by the mucus, and if the stomach 

 has been washed, so to speak, in this manner several times in succession, 

 not unfrequently all connection between rate of secretion and degree of 

 acidity can be removed. That is to say, the juice is equally and strongly 

 acid whether it be rapidly or slowly poured out. On the other hand, 

 Dr. Ketscher has collected the juice in the following way during the 

 course of the same sham-feeding experiment for periods of five minutes 

 duration each. During one five minutes the fistula remained open, 

 during another it was kept closed, and the juice allowed to escape at 

 one rush. It resulted, in nearly all cases, that the portions of juice 

 obtained in the second way i.e., after a delay of five minutes in the 

 stomach, possessed a lower acidity than the others. And if fluctuations 

 of acidity can occur in this way with pure gastric juice, all the more 

 easily will they arise in a stomach to which food mixed with saliva can 

 gain access. Moreover, a short time ago we made observations in the 

 laboratory upon a dog suffering from strongly marked hyperacidity of 

 pathological origin. But in no single sample of the juice did the acidity 

 prove to exceed the normal. (1'awlow.) If all this be correct, the 

 varying necessity for acid during the course of digestion is supplied by 

 variations in the quantity of juice and not by changes in its acidity. 

 It is, however, possible that the neutralisation of the gastric juice must 

 be looked upon as a purposive and desirable event with a definite aim. 

 In the normal stomach a perfectly pure juice may have its acidity 

 reduced to the extent of twenty-five per cent, by neutralisation with 

 mucus. Who knows, perhaps nature has found it serviceable in the 

 interests of the organism, or the elaboration of the food, to vary the 

 acidity precisely in this way ! That it does fluctuate remains a fact, 

 however it may happen to come about. 



We may now take up the threads of our discourse once more. You 

 have seen striking instances of the fact that the juice furnished by 



