290 PHOTOCHEMISTRY OF VISUAL PURPLE. II 



—generally near 1.3 (Hober, 1914, p. 708). The fact that the tempera- 

 ture coefficient of visual purple bleaching is 1.00, combined with the 

 other evidence already at hand, would therefore indicate that the 

 kinetics of the reaction represent a real chemical occurrence rather 

 than a process of diffusion. 



SUMMARY. 



The temperature coefficient of the bleaching of visual purple by 

 light is 1.00 over a range of 30 degrees. This indicates that the 

 monomolecular course of the reaction represents a real chemical 

 process, as opposed to a possible diffusion process, and that the 

 reaction is probably simple in nature. 



BIBLIOGRAPHY. 



Hecht, S., (a) The effect of temperature on the latent period in the photic response 

 of Mya arenaria, J. Gen. Physiol, 1918-19, i, 667; (b) The photochemical 

 nature of the photosensory process, 1919-20, ii, 229; (c) Photochemistry of 

 visual purple. I. The kinetics of the decomposition of visual purple by 

 light, 1920-21, iii, 1. 



Hober, R., Physikalische Chemie der Zelle und der Gewebe, Leipsic, 4th edition, 

 1914. 



Kiihne, W., Chemische Vorgange in der Netzhaut, in Hermann, L., Handbuch 

 der Physiologie, Leipsic, 1879, iii, 235. 



Mellor, J. W., Chemical statics and dynamics, London, 1904. 



Osterhout, W. J. V., Some aspects of the temperature coefficients of life processes, 

 J. Biol. Cheni., 1917, xxxii, 23. 



Sheppard, S. E., Photochemistry, New York, 1914. 



