TEMPERATURE AND CRITICAL ILLUMINATION FOR REACTION TO FLICKERING LIGHT : IV. ANAX NYMPHS

At fixed flash frequency (_F = 20, _F = 55) and with constant light time fraction (50 per cent) in the flash cycle, the critical illumination I for response of Anax nymphs to visual flicker falls continuously as the temperature rises. The temperature characteristic µ for the measure of excitability (1/I) increases continuously with elevation of temperature. The form of the F - log I curve does not change except at quite high temperature (35.8°), and then only slightly (near F = 55); F_max. is not altered. The very unusual form of the 1/I curve as a function of temperature is quantitatively accounted for if two processes, with respectively µ = 19,200 and µ = 3,400, contribute independently and simultaneously to the control of the speed of the reaction governing the excitability; the velocities of these two processes are equal at 15.9°.