Urease is found in at least two forms in the seeds of Canavalia; one can easily be extracted by a dilute solution of aceton, and the other is scarecely extractable by the same solvent. The former corresponds to Sum m er's crystalline urease, and the latter was assumed to be non-crystallizable in our previous paper. The ratio of the quantity of these two ureases in Canavalia varies with the species of Canavalia, and also, in the case of the same species, with the growing-environment. The soluble urease is contained in the largest amount in Canavalia ensiformis, which is suitable as material for the isolation of crystalline urease. Owing to isolating two kinds of urease, the meal of Canavalia is extracted at ? 13° twice by seventy-five times its quantity of 37.5 0 aceton which contains 0.10 phosphate. The non-extractable urease remaing in the residue was ascertained to be non-crystallizable.
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