448 



PHOTOREACTIONS OF WHIP-TAIL SCORPIONS 



Table VI and Fig. 6 show the reactions of symmetrically blinded 

 animals to anterior illumination. The experimental conditions under 

 which these measurements wxre made are essentially similar to those 



Fig. 5. Reactions to lateral illumination in animals which had been subjected 

 to symmetrical interference with their photoreceptive mechanism. The circle 

 represents the observation circle of the apparatus; the group of arrows, the direc- 

 tion of the light beam; the silhouette of the scorpion, the animal's position when 

 subjected to lateral illumination; the dotted arrow, the average reaction of nor- 

 mal animals; the solid arrow, the average reaction of the experimental animals. 

 a. Animals with both median eyes capped, b. Animals with both lateral eye 

 groups capped, c. Cutaneous sensitive areas on both sides blackened, d. 

 Both median and both lateral eyes capped, e. Both cutaneous sensitive areas 

 and both lateral eyes blackened. /. All photoreceptors blackened. 



set up when lateral illumination was used. The difference lies only 

 in the greater deflection an animal must make to come into orienta- 

 tion when subjected to anterior illumination. A comparison of Figs. 



