on Amylolytic and Proteolytic Action. 145 
shown that the addition of 0°1 per cent. hydrochloric acid to an 
aqueous extract of the pancreas stops its action, OC. A. Ewald* how- 
ever, found that while pepsin-hydrochloric acid destroyed trypsin, 
trypsin could digest fibrin in the presence of 0°3 per cent. hydrochlo- 
ric acid. Mayst likewise found that trypsin digestion could take 
place in the presence of 0:3 per cent. hydrochloric acid, but only 
when a relatively large proportion of fibrin was present, and in cor- 
roboration of Kiihne’s statement, he showed that trypsin could be 
destroyed both by pepsin and dilute hydrochloric acid. Engesser{ 
found that a pancreatic juice did not lose its tryptic power by two 
hours warming with a gastric juice containing 0°5 per cent. hydro- 
chloric acid. Langley,§ on the contrary, has shown that a glycerine 
extract of the pancreas loses a very appreciable amount of trypsin 
when warmed for two and a half hours with 0°05 per cent. hydrochloric 
acid. Lindberger,|| working with an alcohol precipitate from a glyc- 
erine extract of ox pancreas, in which there would naturally be 
present but a small amount of proteid matter in addition to the tryp- 
sin, found that in the presence of 071 per cent. hydrochloric acid the 
ferment was entirely without action, and even in the presence of 
0°012 per cent. hydrochloric acid, fibrin was much more slowly dis- 
solved than by a neutral trypsin solution. Lindberger, moreover, 
found that weaker acids, as acetic and lactic, had a much different 
effect than the stronger hydrochloric acid; thus with dilute acetic 
acid, digestion of the fibrin was almost as rapid as with a neutral 
solution of trypsin, while with small amounts of lactic acid, fer- 
ment action was even more energetic than in a neutral solution. 
There is, however, no guarantee that in these experiments free acid 
was present. 
We have found that free acids, even when present in small per- 
centages, completely stop the proteolytic action of trypsin, and that 
when considerable albuminous matter is present, the action of tryp- 
sin is much hindered by the addition of acid to a neutral solution, 
even before the proteid matters present are saturated with acid. 0°1 
per cent. free salicylic acid, in the presence of proteids already satu - 
* Jahresbericht fiir Thierchemie, 1880, p. 297. 
+ Untersuchungen a. d. physiolog. Inst. d. Univ. Heidelberg, vol. iii, p. 378, 1880. 
{ Jahresbericht fiir Thierchemie, 1880, p. 297. 
§ Journal of Physiology, vol. iii, No. 3. 
|| Jahresbericht fiir Thierchemie, 1883, p. 281. 
S| We have seen only the abstract of Lindberger’s paper, so cannot speak positively 
on this point. 
TRANS. Conn. Acap., VOL. VII. 19 Oot., 1885. 
