778 



LIGHT AND LIFE 



2.0 



1.5- 



V 



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CO 



<9 

 O 



0.5 



T 1 r 



DARK-ADAPTED 



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DURING ADAPTATION 

 WITH RED LIGHT /""^^ 



OO 



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_L 



J_ 



J_ 



I 



300 



400 



500 



Fig. 2. Alteration of the shape of the spectral sensitivity of the worker honey- 

 bee by selective light adaptation. During a constant level of adaptation brought 

 about by red light, the ultraviolet receptor system contributes more prominently 

 to the spectral sensitivity function (open circles) than it does in the dark-adapted 

 eye (filled circles). Ordinate: logarithm of the reciprocal of the relative number 

 of quanta required to produce a retinal action potential of constant size. (From 

 ref. 20). 



animal. Although ultraviolet light is several times as effective as green 

 in stimulating certain kinds of behavior, this does not necessarily 

 mean that the compound eyes are several times as sensitive to the 

 shorter wavelengths or contain several times as many ultraviolet as 

 green receptors. In the case of the honeybee the basis for the dif- 

 ference in results obtained with the electroretinogram and the whole 

 organism appears to reside in the integrative action of the central 

 nervous system. On the other hand, differences in the ratios of the 

 heights of the two peaks observed in different electrophysiological 

 experiments on the same species probably reflect variations in the 

 proportion of two types of receptors in the field from which the 

 electrode records. 



