MOTOR RESPONSES 



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 LUMINOUS INTENSITY IN METER. CANDLES 



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Figure 106. Graphs showing relation between luminous intensity and reaction time, 

 exposure period, latent period, and energy. Each point on the curves of the reaction 

 time and the exposure period represents the average for ten tests, different individuals 

 being used in each test. Each point on the curve of the latent period represents the dif- 

 ference between the reaction time and the exposure period. Each point on the energy 

 curve represents exposure period X luminous intensity. (After Shettles, 1937.) 



are at least two processes involved in the response of Peranema to light. 

 One of these is nearly independent of temperature and is therefore prob- 

 ably photochemical. The other is closely correlated with temperature and 

 is therefore not photochemical. 



After Peranema has responded in light of a given intensity, it must 

 be subjected to light of a lower intensity or to darkness before it will 

 again respond. The time required for recovery varies directly with the 



