186 



THE PHYSIOLOGY OF INSECT SENSES 



20 



1-5 



> 

 V) 



C 

 -J 



10 



0-5 



Dark Adapted 



During adaptation 

 with red light 



300 



Fig. 91. Alteration of the shape of the spectral sensitivity of the worker 

 honeybee by selective light adaptation. During a constant level of 

 adaptation brought about by red light the ultra-violet 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. 

 (Redrawn from Goldsmith, 1961.) 



ment is less striking because the ultra-violet receptor system contri- 

 butes less to the ERG than the green system and because the sensitivi- 

 ties of the two systems behave differently to different coloured 

 adapting hghts. Nevertheless, these experiments confirm the existence 

 in the bee of two of Daumer's postulated receptor types. The existence 



