THE RELATION BETWEEN LUMINOUS INTENSITY, ADAPTATION TO LIGHT, AND RATE OF LOCOMOTION IN AMOEBA PROTEUS (LEIDY)

¹ From the Zoölogical Laboratory of the Johns Hopkins University

1. The rate of locomotion in Amoeba proteus is definitely correlated with the intensity of the light to which it is exposed and the state of adaptation.

2. In light of any given constant intensity, as adaptation to light increases, the rate of locomotion increases to a maximum and then remains constant, but in constant light of different intensities, the time required for adaptation decreases from about 15 minutes at 225 m.c. to a minimum of about 7 minutes at 15,000 m.c. and then increases to about 30 minutes at 40,000 m.c. and the rate of locomotion increases from 128.8 ± 10.8 micra per minute at 50 m.c., to a maximum of 219.3 ± 11.4 micra per minute at 15,000 m.c., and then decreases to 150.2 ± 8.5 micra per minute at 40,000 m.c.

3. Increase in rate of locomotion with increase in intensity to optimum at 15,000 m.c. is largely due to some unknown action of the longer waves of light. Decrease in rate with increase in intensity beyond the optimum is probably due to the gelating action of the shorter waves of light.