450 



PHOTOREACTIONS OF WHIP-TAIL SCORPIONS 



DISCUSSION. 



Relative Effectiveness of Photoreceptors. 



The relative effectiveness of the lateral eye groups, the median 

 eyes, and the cutaneous photosensitive areas should be indicated by 

 the changes from the normal reactions produced by their elimination. 

 Table VII is a summary of the data secured by unilateral and bilat- 

 eral elimination of each of the photoreceptors. The change from the 

 normal reaction is given (1) in degrees of deflection; (2) in per cent 



TABLE VII. 



Summary of Effects of Eliminating Different Members of Photoreceptive Mechanism. 



of the normal reaction; and (3) in relative values calculated by taking 

 the change produced by elimination of the median eyes as unity. 



There are certain apparent inconsistencies in the data of Table VII 

 that require consideration before we attempt to draw any conclusions 

 as to the relative effectiveness of the photoreceptors. 



There is good agreement between the reductions in normal reaction 

 produced by the elimination of the median eyes under lateral and 

 under anterior illumination, the value of the reduction from normal 

 being 10 per cent under lateral illumination and 9.2 per cent under 



