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The temperature characteristics of growth of microorganisms and other organized biological processes bear a formal relation to the energies of activation of enzymically and non-enzymically catalyzed reactions. Although certain variations, observational or real, occur in these energy values with temperature, velocity extrapolations justified within reasonable limits lead to some valuable considerations. 1. Extrapolations to cold storage temperatures show the relatively enhanced importance of unorganized enzyme reactions compared to microbial action or non-enzymically catalyzed reactions. 2. Materials whose constituent ferments have high energies of activation will be aided most by storage at low temperatures. 3. The magnitude of the various changes that occur in a single product will not all be quantitatively altered in the same degree by lowering the temperature, as evidenced by the differences in fruits ripened at low and at ordinary temperatures. 4. From the activity and temperature characteristic data of reactions in any particular product at ordinary temperatures it should be possible to predict the nature of the major changes that would occur in storage. In the critical region of temperature where liquid systems become frozen, generally 0 to -5°, the extrapolation of reaction velocities is, as might be expected, no longer readily feasible. Determinations with cathepsin, chymotrypsin and pancreas lipase show that in some, but not all, cases the velocity of simple enzyme reactions is greatly decreased when the change of state occurs.

Male Swiss-Webster mice weighing 18 to 22 gm. were employed.All animals were observed through 72 hours.Rats.

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