502 APPENDIX. 



entirely suspends its solvent action, although the m'xture still 

 exhibits a decided acid reaction. 



This latter experiment distinctly explains how it is that, when 

 still undigested albuminous matters pass into the intestine, the 

 gastric juice loses all power over them. If there be an acid 

 reaction in the duodenum, this does not depend upon the presence 

 of free hydrochloric acid, but on that of the biliary acids isolated by 

 it. Since these are either very readily resorbed or else are insoluble, 

 we commonly fail to observe an acid reaction in the jejunum even 

 after the use of a flesh-diet. 



With regard to the quantities of albuminous substance which 

 can be dissolved by definite quantities of gastric juice, I have 

 found that 100 grammes of the fresh gastric juice of the dog are 

 able, on an average, to dissolve 5 grammes of coagulated albumen 

 (this being the mean of eight experiments, in which the extremes 

 were 6" 14 and 4*317 grammes). Schmidt, who instituted similar 

 experiments, arrived at a far lower result : as a mean of 27 experi- 

 ments, he found that 100 grammes of gastric juice dissolved 

 only 2*2 grammes of albumen ; the highest number which Schmidt 

 found being 3*95 grammes. The method which I pursued in these 

 investigations was the same as that which I adopted in my experi- 

 ments with artificial gastric juice. The higher numbers which I 

 obtained were probably dependent on the presence of lactic acid 

 in the fresh gastric juice, while Schmidt only operated on gastric 

 juice in which there was no lactic acid. Since many conditions 

 favouring the solution of the protein-bodies co-operate within the 

 stomach, and since the gastric juice obtained from fistulous open- 

 ings probably possesses less digestive power than that which is 

 secreted from uninjured stomachs, Bidder and Schmidt very 

 correctly infer that the gastric juice may be able to dissolve a 

 larger amount of albuminous matter than the results of our 

 experiments would seem to show. 



Now, if we know the quantity of the gastric juice which is 

 secreted in twenty-four hours (see the preceding page), [and 

 the quantity of albumen which is dissolved by a definite quantity 

 of gastric juice, we can readily ascertain the quantity of albumen 

 which can be daily digested in the stomach. Since a dog secretes 

 about 100 grammes of gastric juice for every kilogramme's weight 

 of its body, that animal would only be able to digest 5 -jj- of its weight 

 of albumen (reckoned as dry). But it appears from the numerous 

 experiments of Schmidt, that a dog, in order to keep in condition 

 on an exclusive flesh-diet, should take for every kilogramme's 



