A RETINAL MECHANISM OF EFFICIENT VISION 353 



Although responses may be initiated at lower intensities, in 

 general an approach to a maximal light response is first elicited 

 at an intensity which makes ordinary print legible. 



Since the responses in dim light approximate those in total 

 darkness, the mechanical conditions are present for a theo- 

 retically more efficient dim-light and bright-light vision than 

 would otherwise obtain. This increased efficiency depends 

 upon the assumption by these elements of correlative advan- 

 tageous positions. 



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