The decomposition of pepton in silk-worm tissues increased several hours after the injection of polyhedral solution and the decomposing activity was higher in survived larvae than in untreated ones. The pepton-hydrolysing enzyme is activated by the injection of nucleus from silkworms in the eclipse period. The enzymatic activity in virus-diseased individuals is much stronger than that in healthy ones. An activation of the enzyme is caused by hydroxylamine feeding. The activity of acetone preparations is somewhat elevated by hydroxylamine but is not influensed by hydrogen peroxide and thyoglycolic acid.