SELIG HECHT 517 



basis of these ifindings it is suggested that visual reception in dim 

 light is conditioned by a reversible photochemical reaction involving a 

 photosensitive substance and its two products of decomposition. 

 Accordingly, dark adaptation depends on the course of the "dark" 

 reaction during which the two products of decomposition reunite to 

 synthesize the original photosensitive substance. 



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