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HENRY LAURENS 



noon in order that the hght might have had as strong an effect 

 immediately before the experiments as possible. The jars in 

 which the larvae were kept, were placed on a broad wihdow-sill 

 of a room into which the dark-room opened, and a larva could 

 be placed and oriented in the testing dish within twenty sec- 

 onds of the time that it was first picked up. 



The results of this series of tests are shown in tables 4 and 5. 

 It was soon found that the condition of the pigment in the skin 

 chromatophores does not affect the sensitiveness of the larvae 



TABLE 4 



Photic reactions of normal Amblystoma larvae, after previous exposure in the 



light or in the dark 



TABLE 5 

 Photic reactions of eyeless Amblystoma larvae after previous exposure in the 



light or in the dark 



