1905] DEAN—PROTEOLYTIC ENZYMES 129 
the digestion the contents of each flask were strained through cotton 
gauze, and 20°° of each fluid precipitated with an equal volume of 
tannic acid reagent. Duplicates of 15°° each from both filtrates 
were analyzed for nitrogen. 
Nitrogen in analyses of filtrates of unboiled digestion =o .00368™ 
Nitrogen in analyses of filtrates of boiled digestion =0.0035&™ 
It is therefore evident that no enzyme capable of acting on the native 
proteids of the bean is present in the young hypocotyls. 
COMPARATIVE CONTENT OF EREPTASE IN VARIOUS TISSUES OF 
PHASEOLUS VULGARIS 
In making any study of the relative quantities of ereptase in dif- 
ferent tissues it is necessary to have some basis of comparison. 
Manifestly the dry weight of vegetable tissues is not a very satisfactory 
standard, since in many cases the cell walls constitute the greater 
part of the dry weight. The ideal way would be to use the weight 
of protoplasm as a basis for comparison, but this is out of the ques- 
tion. The best substitute seemed to be the quantities of the nitro- 
gen in the tissues. The first measurements of the amount of ereptic — 
activity in the tissues were carried out in the following manner. 
Nitrogen determinations were made on the fresh tissues to be tested, 
and then portions of each tissue, of such a weight that each portion 
contained 0.028" of nitrogen, were weighed out into small tared 
flasks. Into each flask 10° of a 10 per cent. Witte peptone solution 
were measured and the total weight of the digestion made up to 
25®™ by the addition of distilled water. After the addition of 1° 
of toluol to each digestion the flasks were tightly corked and kept in 
the incubator for twenty-four hours at 41° C., the contents of each 
flask being shaken twice during that period. At the close of the 
digestion each mixture was strained through dry cotton gauze, and 
20° of each fluid mixed with 20°¢ of tannic acid reagent. .The 
Precipitates were filtered off on dry filters and the filtrates analyzed 
for nitrogen in duplicates of 1 5°° each. Minor changes were made 
.in this procedure in the subsequent series of determination, so that 
the results obtained thereby were not strictly comparable with the 
t series; since it was impossible to test the same tissues again the 
results of the first, and less satisfactory series, are nevertheless given: 
