1905] DEAN—PROTEOLYTIC ENZYMES 325 
to cause some doubt in respect to the universal occurrence of pro- 
teases in living tissues, and the positive results were obtained with 
such a diversity of tissues that they do not lead to any definite hypothe- 
sis of the physiological réle of these enzymes. In view of the evidence 
of VINES’ researches, it appears probable that a more thorough 
study of the tissues examined by Fermi and Buscatront would 
show that proteases are present there which cannot act under the 
conditions of their experiments. Their positive results support 
: the theory of the universal distribution of proteolytic enzymes, 
their negative results do not disprove it. 
Finally we come to a consideration of the results of VinEs."3 
He believes that all vegetable proteases are proteolytic in distinction 
from peptonizing, i. ¢., that they change the proteids which they 
attack into their ultimate cleavage products, amido-acids, hexon 
bases, etc., and do not stop, like pepsin, with the albumoses and 
peptones in preponderance. Acting on this well-justified assump- 
tion, he expects to find tryptophan as the result of the action of 
vegetable proteases, and uses as a test for proteolysis the progressive 
formation of tryptophan as shown by the color reaction with chlorine 
or bromine water. He uses the method of autolysis, allowing the 
€nzymes of a tissue to digest the proteids of that tissue and from 
time to time tests samples of the mixture for tryptophan. He fre- 
quently adds other proteids to the digestion, especially Witte peptone. 
The only objection to the method is that some proteids do not contain 
| the tryptophan group, or only a small amount of it. A negative 
. tesult by Vines’ method with a tissue containing such a proteid would 
7 hot mean much. This probably explains the differences between 
the results obtained by Vines and BuTKEWwITscH in their exam- 
inations of the germinating seeds of Vicia Faba, since OSBORNE 
and Harris‘ have shown that the proteids of this seed give but 
4 faint Adamkiewicz reaction, a reaction which Hopkins and 
CoLe"s have shown to be due to the presence of the tryptophan 
Stoup in the proteid molecule. By using Witte peptone, VINES 
obtains evidence of proteolysis in cases where the tissue contains 
a a 
13 VINEs, Annals of Botany 16:1. 1902; 1'7:237 and 597. 1903; and 18:289. 1904. 
“4 OSBORNE and Harris, Jour. Am. Chem. Soc. 25:853- 1903- 
*S Hopkins and Cote, Jour. Physiology 27:419- 1901. 
