334 BOTANICAL GAZETTE [way 
Cotyledons of etiolated seedlings thirteen days old.—These cotyledons 
gave convincing evidence of the presence of ereptase, but no tryptase. 
Besides testing the cotyledons of germinating beans by the method 
of autodigestion, extracts were also prepared with glycerin and 20 
per cent. alcohol. The tests applied to these extracts showed that 
they were incapable of digesting the bean proteids or boiled fibrin. 
It should be noted that OsporNE and Harris‘? have found that 
phaseolin, the globulin which makes up the main proteid store of 
the resting bean, gives but a faint Adamkiewicz reaction. Therefore 
the absence of a tryptophan reaction in the autodigestion experiments 
with the bean cotyledons would not be conclusive evidence of the lack 
of proteolysis. The use of the Millon’s reaction for tyrosin and 
the biuret reaction for albumoses and peptones would have shown 
the presence of the products of peptonization or proteolysis had they 
been present. Still more conclusive evidence that the enzyme in 
question does not act on the unaltered proteids of the cotyledons is 
afforded by the more thorough study of the enzyme. 
Beans were allowed to germinate for four days and the cotyledons 
separated and ground in a mortar to a paste. Forty grams of this 
pulp were extracted with 200° of water and 5° of toluol. The 
extract was removed from the tissue residue by straining through 
fine muslin, and, since phaseolin is soluble in water and the salts 
of the seed, this milky looking fluid was rich in proteid matter. The 
200°° of extract were divided between two flasks and one of the por 
tions boiled. After digesting for seventeen and one-half hours, 
a comparative quantitative estimation of the amount of nitrogen in the 
proteid decomposition products was made in the following manner. 
Fifteen cubic centimeters of each digestion fluid were mixed ina dry 
beaker with 1 5°° of tannic acid reagent (7 per cent. of tannic acid 
dissolved in 2 per cent. acetic acid) and the precipitates removed by 
filtration. Nitrogen determinations were made in duplicate by the 
Kjeldahl method on 5° of each filtrate. The amount of standard 
acid required to neutralize the ammonia formed by the sulphuric 
acid treatment was, in the unboiled digestion, 0.7°°; in the boil 
digestion 0.5°°. The digestions were allowed to proceed for two 
17 OSBORNE and Harris, Joc. cit. 
