Abstract
4-Methylumbelliferone-beta-D-glucoside was prepared and used as a fluorigenic substrate for the assay of beta-glucosidase. The enzyme was found in tissues of locust, cockroach, flour beetle, greater water boatman, black aphis, rat, guinea pig, ferret, and rabbit. The pH optimum is 5.1 - 5.7. The enzyme of locust-crop fluid is shown to be different from the beta-glucuronidase present. In both insects and mam-mals, enzyme seemed to be lowest in concentration in carnivores. Re-lated to this may be the decreased susceptibility to amygdalin in these species.