Temperature Characteristics for the Growth of the Sporangiophores of Phycomyces

1. With constant temperature and light intensity, the rate of elongation of a sporangiophore of Phycomyces is constant for many hours. 2. With constant light intensity, values of micro, the "critical thermal increment," have been computed for the elongation of different sporangiophores. These values group themselves closely about the modes 11,000, 16,000, 20,000, 26,000, and 33,000 calories. Sporangiophores from the same culture need not have similar increments. 3. The significance of these results for studies of growth is discussed.