144 Chittenden and Cummins—Influence of Bile 
With a larger “percentage of fibrin and a longer period of diges- 
tion the results are somewhat different. The following were obtained 
with 4 per cent. of fibrin in 6 hours and 40 minutes at 40° C.: 
Reaction of Weight of Fibrin 
the fluid. undigested residue. digested. 
neutral 0:3785 gram. 62°15 per cent. 
0°1 per cent. NazCO; 0°2581 74:19 
0°2 0°1395 86°05 
0°3 0°1588 84°12 
0-4 0°1629 83°71 
0°5 01318 86°82 
0'1 pr. ct. salicylic acid  0°4728 52°72 
An average of the two series of results plainly shows that there is 
but little difference in digestive action in the presence of 0*2-0°5 per 
cent. sodium carbonate, although in a given solution a change in the 
percentage of alkali is at once manifest, to a slight extent, in the 
amount of fibrin digested. Greatly increased percentages of alka- 
line carbonate materially diminish the action of the ferment, as the 
following series of experiments indicate; the mixtures were warmed 
for 2 hours at 40° C.: 
Reaction of Weight of Fibrin 
the fluid. undigested residue. digested. 
neutral 0°5863 gram. 41°37 per cent, 
0°5 per cent. Na,CO; 0°1584 84°16 
10 0°3760 62°40 
2°0 - 0°7010 29°90 
3°0 0°7892 21:08 \ 
4:0 0°8373 16°27 
5-0 0°8608 \ 13°92 
The difference in action between a neutral trypsin solution and a 
solution containing salicylic acid is quite noticeable, at the same time 
it is evident that in the acid-reacting fluid the ferment simply acts 
more slowly, and if time be given, the action will approach more 
closely to that of the neutral solution. It is of course understood 
that the salicylic acid in the above experiments does not exist in a 
free state, but in combination with the proteid matter present, and 
doubtless in most of the experiments recorded, where trypsin has 
been exposed to the action of small fractions of a per cent. of acid, 
no free acid has been present, but only varying percentages of acid- 
proteids.* Kiihnet has pointed out that hydrochloric acid above 0°05 
per cent. is injurious to the action of trypsin, and Heidenhain{ has 
* See Danilewsky. Centralbl. med. Wiss., 1880. 
+ Verh. Naturhist. med. Vereins zu Heidelberg, 1877, p. 193. 
+ Pfliiger’s Archiv, vol. x, p. 578, 
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PEA te eg SELEY IOS 
