552 Vines . — T he Proteolytic 
admit that, as pointed out in my paper of last year, I have 
by no means always succeeded in obtaining a more active 
extract as the result of treatment with acid ; on the contrary, 
I have frequently found that previous treatment of the pitchers 
with acid diminished instead of increasing the activity of the 
glycerin-extract. I do not regard these apparent contra- 
dictions as wholly attributable to various conditions of the 
pitchers, for I have obtained sometimes quite opposite results 
with pitchers as nearly as possible of the same age, and 
sometimes quite similar results with pitchers of different ages 
( e.g . opened and unopened). On the contrary, my results 
seem to show that the differences in the activity presented 
by the various acid-extracts are due rather to the mode of 
treatment of the pitcher-material. It would appear that the 
most effectual mode of decomposing the zymogen is to act 
upon the tissue with acid for a short time at a relatively 
high temperature (see example of June 2-10). More prolonged 
treatment at a lower temperature (say 35 0 C.) would seem to 
cause not only the liberation of the enzyme, but also its 
extraction from the glands in connexion with the digestion 
of the pitcher-tissue itself. 
I may just point out in conclusion that the marked acidity 
of the liquid in the unopened pitcher is no doubt to be 
connected with its high digestive activity ; whilst the acid 
is useless for digestive purposes until the opening of the 
pitcher, it is probably of importance in that it acts upon 
the zymogen, liberating the enzyme. 
The Products of Digestion. 
In my paper of last year I pointed out that the chief proteid 
product of digestion was a substance closely resembling 
deutero-albumose, and I stated further that I had failed to 
detect the presence of a true peptone, that is, of a proteid 
which is not precipitated on saturation with ammonium 
sulphate. I have, however, since detected the presence of 
peptone, though in relatively small quantity, among the 
products of the digestion of fibrin by the pitcher-liquid. 
