TEMPERATURE AND LOCOMOTION IN PLANARIA

A consideration of the temperature characteristics or thermal increments for locomotion in Planaria shows that they agree essentially with those reported for certain activities of other animals (Crozier, and Glaser). A process with the lowest increment (µ = 7,000 to 8,000) assumes control of the locomotor rate at temperatures above 20–22°; that with the highest increment (µ = 18,000 to 22,000) controls below 13°; and one with an intermediate value (µ = 11,100) is in command at the intermediate temperatures (13–21°). Another reaction with increment µ = 14,600 may, under certain conditions (e.g. 2 weeks after feeding), control the series over the median range. Excepting the latter, these increments are typical of catalyzed oxidative reactions (Crozier 1924–25, b) so that when these are in control it may be assumed that respiration is the fundamental process determining the rate of locomotion. Feeding produces a modification of the increment throughout the median range of temperatures, up to 2 days afterward.