of the, Salman in Fresh Water. 33 



The chlorine present in the form of chlorides or of hydrochloric acid 

 only amounted to 0*00489 grammes or -00978 per cent, as HC1, while 

 0*0148 grammes of hydrochloric acid had to be added before positive 

 evidence of free mineral acid was obtained, or 0*0296 per cent. If the 

 proportion of HC1, combining to proteid bodies be taken at 10 per cent. 

 (Of. Journ. Anat. and Phys, Vol. XXVII., p. 195} 0*148 grammes of 

 proteid was present unattached to this acid. 



Similarly it was shown that 0*0204 gramme of silver nitrate combined 

 with organic material, which represents about 0*21 gramme of proteid. 



From this stomach and its contents, therefore, no free mineral acid 

 was obtained, but only a small quantity of combined hydrochloric acid 

 and some organic acids. 



The alcoholic extract of the chopped-up stomach of Fish No. XXVI., 

 June 1896, caught in the upper waters, was mixed with ether, 

 agitated, and then an excess of distilled water added. The water was 

 separated from the supernatant ether and distilled to dryness ; 0*00684 

 gramme of free hydrochloric acid was obtained in the distillate, and no 

 orgiiiiic acids were present. 



The alcoholic extracts of the stomachs of three salmon caught in July 

 1895, a kelt, a fish which had been some time in fresh water, and a fish 

 caught at the river mouth, showed no evidence of the presence of free 

 hydrochloric acid, and were only slightly acid to litmus. 



The gastric mucous membrane of salmon on their way to the 

 spawning beds yielded no free hydrochloric acid to the alcohol (90 per 

 cent.) in which it was immersed, but investigation showed the presence 

 of some hydrochloric acid in combination with organic material. The 

 alcoholic extract, however, contained a volatile organic acid which 

 readily distilled over, and an organic acid which did not pass off' on 

 distillation. In one fish caught in the upper waters in June a small 

 quantity of free hydrochloric acid was obtained from the alcoholic 

 extract of the stomach, after distillation to dryness. 



The almost constant coincidence of an increased acidity of the 

 glycerine extract of the stomach with an enhanced digestive power must 

 be regarded as being independent of the presence or absence of 

 hydrochloric acid. Other acids are known to exert an appreciable 

 power when acting in the presence of pepsine, and presumably, there- 

 fore, are capable of converting to some extent the forerunner of that 

 ferment, pepsinogen, into active pepsine. The extracts were made 

 from the chopped-up walls of the stomach and its mucoid contents, 

 the acid present in the mucus and formed by bacterial action may 

 have acted on the pepsinogen and converted part of it into pepsine. 

 But the results of the bacteriological cultivations do not bear out this 

 theory, as, with two exceptions, the fewer the organisms the greater 

 was the power of the gastric extract. 



Another difficulty, and a serious one, is afforded by the fact that the 

 glycerine extracts, although made after immersion in alcohol for 48 

 hours or more, varied greatly in acidity, though without the presence of 

 any bacterial decomposition. The peptic power with two exceptions 

 corresponded with the acidity as determined. 



It is impossible to even hazard any theory to account for the 

 apparent paradox, and it only remains to state that the greater the 

 acidity the fewer organisms, and the greater the peptic power of the 

 ferment in the stomach, although the acidity of the extract may not 

 be due to free hydrochloric acid. 



5. TRYPTJC DIGESTION. 



In a few instances the activity of the tryptic ferment of the 

 c 



