ee ee ae ee 
ON PROTEOLYTIC ENZYMES. II. 
ARTHUR L. DEAN. 
SINCE the writing of the previous paper" on the vegetable pro- 
teolytic enzymes, an article by VERNON? has appeared in which he 
gives an account of his investigation of the distribution of erepsin in 
the animal body. Comparative tests were made of glycerin extracts 
from thirteen different tissues of the cat, eight of the rabbit, eight of 
the guinea pig, seven of the pigeon, eight of the frog, seven of the eel, 
six of the lobster, and three of the fresh water mussel. In every case 
an erepsin was found to be present. ‘The comparison of the activity 
of the various extracts was effected by means of colorimetric estima- 
tions of the intensity of the biuret reaction after certain periods of 
digestion. The tissue extracts from the warm blooded animals were 
more active than those from the cold blooded animals; the extracts 
from the invertebrate tissues had a relatively slight action. In the 
warm blooded animals it is not the intestinal mucous membrane 
which is richest in erepsin, but the kidney in the cat, rabbit, and 
pigeon, and the pancreas in the case of the guinea pig. 
It might be noted that VERNON gives no record of experiments 
made with the various extracts to determine whether or not they are 
incapable of digesting the proteids of the tissues in which the enzymes 
occur. His experiments, being all conducted with Witte peptone 
solutions, do not conclusively show that the enzymes whose activity 
Was observed are incapable of acting on any proteids except albu- 
moses and peptones. : 
In a former communication evidence was given to show that 
Phaseolus vulgaris contains in its seeds a fairly active proteolytic 
enzyme. No action of this protease on the proteids of the seed could 
be demonstrated. Its power to act on Witte peptone as a whole, 
and on the albumose fractions separated from it, could be readily 
shown. Moreover, as germination progressed the cotyledons at all 
Stages contained this ereptase and at no period of germination could 
* Dean: Bor. Gazerre 39: 321. 1904. 
* VERNON: Jour. Physiol. 32: 33- 1904. 
t 905] 121 
