576 Vines . — The Proteolytic Enzyme of Nepenthes. 
of 25 c.cm. of o* 5 °/ 0 solution of HC 1 and 15 c.cm. of the i°/ o 
solution of Na 2 C 0 3 . The amount of liquid in each case was now 
1 15 c.cm., and the amount of salts in each was identical. C 0 2 was 
then passed through both liquids for an hour: then 15 c.cm. of each 
were placed in a tube, 10 c.cm. of o*5°/ o HC 1 being added to each, 
together with o-i grm. of fibrin, and the tubes were placed in the 
incubator to digest at 1 p.m. At 3 p.m. the fibrin in both tubes was 
entirely dissolved, showing that their activity was the same. 
On repeating the experiment, prolonging the treatment 
with C 0 2 to an hour and a half, I obtained the same result ; 
whence I conclude that the liquid contains no zymogen. 
The general conclusion at which I arrive is that either the 
enzyme is not a proteid, or, if it is, it is present in extremely 
minute quantity, though it is difficult to accept this alter- 
native in view of the remarkable digestive activity of the 
liquid. 
Activity of Glycerin-extracts. 
I have repeatedly confirmed my observation of 1877 that 
active glycerin-extracts of the pitchers can be prepared : in 
but few cases have I found these extracts, when fresh, inopera- 
tive on fibrin, though they acted much less rapidly, as might 
be expected, than the pitcher-liquid. In my experiments of 
1877, and in the earlier ones of this series, the preparation 
of the extract was preceded by treatment of the pitchers for 
some hours with absolute alcohol. But recently I have found 
that a more active extract can be prepared by treating the 
pitchers, finely cut up, at once with pure glycerin, omitting 
the treatment with absolute alcohol. The glycerin is left in 
contact with the pitcher-material for at least a week before 
filtering off and using for an experiment. The pitchers used 
were in all cases vigorous, either opened or unopened. The 
following experiment affords some idea of the relative 
activity of two glycerin-extracts, the one prepared with, the 
other without, previous treatment of the pitcher-material 
with absolute alcohol : — 
