Abstract
1. The critical thermal increments are calculated for respiratory processes (O2 consumption, CO2 production) in various plants and animals. They are characteristically found to be of two, possibly three, types: µ = 11,500, and 16,100 or 16,700. The first is commonly encountered above 15°, the second below that temperature, but these relations may be reversed. (The value of µ may be significantly changed in inanition.)