i6o Vines. — The Proteases of Plants (//). 
It would appear from these results that the protease is contained 
in the latex and not in the tissues. In connexion with Experiment 2 
I incidentally made an observation of some interest that has a bearing upon 
the foregoing conclusion. On testing the reaction of the leaf-extract, I was 
surprised to find that it was not acid, as is generally the case with vegetable 
extracts. It seemed to be somewhat alkaline, and further inquiry proved 
it to be amphoteric. The latex dropping from an injured leaf was strongly 
acid. However, at the close of the digestion-experiments the reaction of 
the liquid had become distinctly acid. 
Asparagus officinalis. 
Though the material for these observations consisted not of leaves but 
of shoots, they may be conveniently introduced here. Their interest lies 
in the fact that they afford yet another instance of fibrin-digestion by 
plants. 
(June). On mincing a number of shoots with the machine, enough juice was 
obtained for the purpose of experiment. It was an acid, turbid liquid ; when further 
acidified with acetic acid, boiled and filtered, it gave a marked tryptophane-reaction 
on the addition of 2-3 times its volume of chlorine-water. Since the liquid gives the 
tryptophane-reaction to begin with, it cannot be used for experiments on peptolysis. 
50 c.c. of the expressed juice, with toluol added to 1 %, were put into each of three 
bottles, with \ grm. fibrin; to No. 1, nothing further was added; to No. 2, Na 2 C 0 3 
to 1 % ; to No. 3, HC 1 to 0-16 %. 
After 22 hours in the incubator, the fibrin was found to be mostly digested in 
Nos. 1 and 3, and apparently unaltered in No. 2 ; 24 hours later it had disappeared 
in Nos. i and 3, and was partly digested in No. 2. 
Cucurbita Pepo var. ovifera. 
I may also include some observations on the digestion of fibrin by the 
Vegetable Marrow. I have not always succeeded with this material : but 
the following are the details of a successful experiment. 
Part of a green, not quite ripe, Marrow, with the rind, was minced, and from the 
tissue 300 c.c, of expressed juice were obtained : go c.c. of it were put into each 
of five bottles with 0-2 grm. fibrin, and there was further added — to No. 1, nothing; 
to Nos. 2, 3, 4, g, HC 1 to o-i, 0-2, o-g, o-g % respectively, and to No. 5 some toluol. 
After 2 2 hours in the incubator, the fibrin had disappeared in all the bottles ; and 
their contents all gave marked tryptophane-reaction. 
It may be useful to those interested in the investigation of proteolysis 
in plants if I append a chronological summary of all the known cases, 
which have been adequately examined from the chemical point of view, of 
the digestion of fibrin or albumin — cases, that is, which indicate the pre- 
sence of a protease other than erepsin. The dates given are those of the 
publication of papers. 
