V. J. WULFF 227 



previously established and of recently obtained evidence, with especial 

 reference to 1 1 changes in the absorption spectrum and the kinetics of the 

 bleaching jirocess of rhodopsin, both in solution and in intact retinas, at 

 temperatures above 0°C (very slow, if any bleaching occurring at tempera- 

 tures below 0°C), and £) the latent period and magnitude of the retinal 

 action potential. With respect to 3, the latent period becomes shorter with 

 rise in temperature, Qio values having been found to range from 2.3 to 

 4.0. whereas the magnitude of the action potential is only slightly affected 

 by temperature, the Qi„ values ranging from 1.0 to 1.3. The effect of tem- 

 perature on these processes is discussed in terms of a kinetic model of two 

 coupling processes: an electrochemical process generating the retinal ac- 

 tion potential, and a timing i^rocess controlling the duration of the latent 

 jieriod. 



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