240 APPLIED PHYSIOLOGY 



secreted, and not by the outpouring of a more acid 

 juice. The time at which free HC1 appears varies with 

 the composition of the food ; the richer the latter is in 

 protein, the longer is the appearance of uncombined acid 

 delayed, for protein has a high acid-binding power. It 

 is for this reason that foods rich in protein are recom- 

 mended in cases in which the production of HC1 

 tends to be excessive. If free HC1 appears early it 

 disappears soon, and the later it appears the longer it 

 lasts, but the average duration of its presence is probably 

 about one and a quarter to one and a half hours. It is 

 of interest clinically to know that after an ordinary 

 Ewald's test-breakfast, free HC1 is always quite evident 

 in an hour (Penzoldt). The stomach is always and at 

 all times acid to litmus, although at the beginning and 

 end of digestion the reaction is very feeble. 



The total acidity of the stomach contents an hour 

 after a test-breakfast (Ewald's) varies from O'll to 0'26 

 per cent, in different individuals, and the proportion of 

 free HC1 from 0*07 to 0'2 per cent. These differences 

 are apparently due to individual peculiarities. The pro- 

 duction of acid seems to be greater in young and healthy 

 subjects than it is in the old, and in 40 per cent, of 

 persons above the age of fifty free HC1 is absent 

 altogether (Seidelin),* a fact which should be borne 

 in mind a- propos of the diagnostic value of the absence 

 of free HC1 in cases of carcinoma. 



It will be obvious from the above description that 

 abnormalities of gastric secretion may arise in several 

 ways : (1) The total amount of juice produced may be 

 * Abst. in Archivf. Verdcwungskrankh., 1904, x. 426- 



