The studies on the changes of the activities of cathepsin, amylase and phosphatase in the enzyme solution extracted from the organs and tissues led to the following results. Report I. As the fundamental experiment, the activities of Papayotin and Taka-diastase which hydrolysed the substrates (gelatine and starch) was kept still after 144 hours in an incubator, but the activities of them in their mixed solution was lost more rapidly. Report 2. The activities of cathepsin and phosphatase in the enzyme-solution extracted from the liver and the activity of phosphatase from the femur of the dog was kept still in an incubator after 20 days, but the activity of amylase from the liver was already lost after 3 or 4 days. Report 3. The activities of amylase in the brain, lung, liver, kidney and the thighmuscle of the rabbit was lost 24 to 36 hours after death in summer, 60 to 72 hours in spring and autumn, but was kept still 72 hours in winter.