The Proteolytic Enzyme of Drosera. 135 
then washed in pure distilled water. The solution was acidulated with 
dilute phosphoric acid, and then a thin mixture of chalk and water was 
added, drop by drop, until the effervescence ceased. The mixture was 
allowed to stand for 24 hours, when the clear fluid was removed. 
“The precipitate was treated with very dilute hydrochloric acid, and the 
result treated with a saturated solution of pure cholesterin prepared by 
Bencke’s method in a mixture of absolute alcohol and absolute ether. The 
mass which separated was then dissolved in absolute ether, and in the 
resulting water was suspended a greyish flocculent matter which was found 
to be perfectly amorphous. It was dried at a temperature of 42°C. When 
applied to a small quantity of fresh milk, the latter was observed to become 
coagulated.” 
This method appears to be exceedingly cumbersome, and the results to be 
unsatisfactory from the standpoint of proteolytic enzymes, as the ferment 
isolated was only noted to cause a viscid coagulation in milk. Besides, it is 
always possible that the cholesterin used might be contaminated with traces 
of various kinds of enzymes. 
Vines* precipitated a proteolytic enzyme from the pitchers of Nepenthes 
in the following manner :—To a certain volume of liquid obtained from the 
pitchers an equal volume of absolute alcohol was added. To increase the 
bulk of this precipitate phosphoric acid and then lime water were added. 
Ammonium carbonate was added until the liquid became neutral, and the 
precipitate was filtered off. Some of the precipitate was shaken up with 
0°2-per-cent. solution of HCl, and this liquid was again filtered, when the 
clear filtrate was found to actively digest fibrin. 
In order to determine the true state of affairs concerning the proteolytic 
enzymes of Drosera, if any such do exist, I performed a series of experiments 
in which the enzymes were precipitated from the fresh leaves of the 
following species of Drosera :—D. auriculata, D. Menziesii, D. peltata, 
D. Whattakere. 
The method adopted for their precipitation was practically the same as 
was employed in connection with an investigation of the enzymes and 
latent life of seeds.t| The leaves were cut off from the plants, and all traces 
of foreign matter were removed from them. They were then washed in 
cold boiled water, and again in a strong solution of chloroform, which acts 
as an antiseptic ; in this solution they became quite flaccid. The leaves were 
now chopped up into minute pieces with a sterilised knife, and the fragments 
weighed and put into a bottle containing about 100 c.c. of lukewarm boiled 
* “Ann. Bot.,’ 1897, vol. 11, p. 573. 
+ ‘Roy. Soc. Proc.,’ 1909, B, vol. 81, p. 424. 
