Vines . — The Proteolytic Enzyme of Nepenthes . 577 
Sept. 3, 1 89 7. Three unopened pitchers of N. Mastersiana were 
removed from the plant : the upper third of each pitcher was cut 
off, the contained liquid poured off, and the pitchers, after well 
washing with water and drying, were chopped up fine. Of this 
material 4 grms. were placed in absolute alcohol for 24 hours; 
then rubbed up in a mortar with 40 c.cm. of pure glycerin and let 
stand (extract A ) : other 4 grms. were at once rubbed up in a mortar 
with 40 c.cm. of pure glycerin (extract B). 
On Sept. 13 both extracts were filtered through muslin to remove 
the coarser particles of pitcher-substance. 
On Sept. 14 the following experiment was made: 2-5 c.cm. of 
extract A were placed in a test-tube with 5 c.cm. of o*25°/ 0 of HC 1 
and a shred of fibrin ; similarly, the same quantity of extract B was 
placed with the same quantity of o-2 5°/ 0 HC 1 and a shred of fibrin, 
in another test-tube : the two tubes were placed in the incubator at 
11.45 a.m. At 1 p.m. the fibrin in B showed signs of breaking 
up, whereas this was not observed in A until 2 p.m.: at 4.30 p.m. 
the fibrin in B had entirely disappeared, whilst some still remained 
in A at 5 p.m. but had altogether disappeared by the following 
morning. 
On Oct. 4, 1897, a similar comparative experiment was made with 
the same extracts, an exactly equal amount (Jg- grm.) of fibrin being 
placed in each tube at 1 1 a.m. : the fibrin was entirely dissolved in 
tube B at 4 p.m., whereas in tube A it had not disappeared by 5 p.m., 
and did not disappear after being left in the unheated incubator all 
night, until it had been heated for an hour (9-10 a.m.) on the follow- 
ing morning. 
The glycerin-extracts do not retain their activity for a 
prolonged period, though I am not able to say exactly for 
how long. For instance, in an experiment made on October 4, 
1897, with extracts prepared on December 2, 1896, the fibrin 
showed no change after forty-eight hours. In experiments 
made on October 6, 1897, with extracts prepared respectively 
on May 7 and May 20, the fibrin underwent but little change 
in twenty-four hours. The extracts in question had been 
found to be active when fresh, digesting in a few hours. 
However, I have found an extract two months old to be 
active. 
