2 14 
Vines .— The Proteases of Plants [VII). 
These results clearly indicate the presence of ereptase, and the probable 
absence of peptase. 
I then obtained from Merck of Darmstadt some of his ‘ Maltine ’ and 
of his £ Absolute Diastase 
Experiments with Maltine. 
One grm. treated with ioo c.c. distilled water formed a somewhat viscid, neutral, 
liquid, which was filtered : the filtrate gave a slight turbidity on boiling and on adding 
HN 0 3 , also a distinct xanthoproteic reaction, faint biuret-reaction, but no trace of 
tryptophane-reaction. 40 c.c. of the filtered liquid were put into each of two bottles, to 
one of which 0*2 grm. fibrin, to the other 0-2 grm. Witte-peptone, were added, with a little 
HCN. After being in the incubator for nearly 48 hours, the contents of the bottle 
to which Witte-peptone had been added gave a faint tryptophane-reaction, indicating 
the presence of a small quantity of ereptase : the fibrin in the other bottle underwent 
no apparent change in 70 hours, and the liquid then gave a trace of biuret, but no 
tryptophane-reaction, showing that practically no fibrin-digestion had taken place. 
I thought it worth while to repeat the experiment, using a stronger 
extract of maltine. 
10 grms. were extracted for some hours with 100 c.c. water and then filtered: 
the filtrate was a clear, light-brown, distinctly acid liquid; on boiling a portion of it, 
a considerable precipitate of protein formed and was filtered off, the filtrate giving 
a distinct biuret but no tryptophane reaction. 40 c.c. of the filtered extract were put 
into each of two bottles, to one of which 0-2 grm. of fibrin was added, to the other 
nothing, in order that it might serve as an experiment in autolysis. Within 24 hours 
the fibrin had nearly disappeared: in 42 hours it had disappeared completely; the 
liquid in the bottle now gave marked tryptophane-reaction. The liquid in the other 
bottle gave a similar tryptophane-reaction at this time. 
To test further the ereptic action of maltine, 0-2 grm. of Witte-peptone 
was digested with 40 c.c. of a 4 % extract: within 24 hours the liquid gave 
a marked tryptophane-reaction. 
Hence it appears that maltine contains proteases capable of digesting 
fibrin and Witte-peptone as well as its own proteins. 
Subsequent experiments were made exclusively with absolute diastase, 
as it was found to digest much more actively than maltine. 
Experiments with Absolute Diastase. 
As the general method of these experiments was similar to that 
of those made with maltine, it will not be necessary to give full details 
in every case. It will suffice to say that distilled water was always used in 
making the extracts; that the antiseptic was HCN; that the temperature 
of the incubator was about 40° C.; and that several control-experiments 
were made with boiled extract, always with negative result. 
