264 



Experimental Zoology 



Here also I question whether the results have any certain value 

 because of the variability shown by tadpoles reared in dishes, and 

 on account of the difficulty of keeping the other conditions the 

 same. 



Vernon's results with sea-urchin larvae are more significant, 

 because the growth, in this case, depends little, if at all, on the 

 food supply. 



LENGTH 



Semi-darkness 



Complete darkness 



Blue (copper sulphate) 



Green 



Blue (Lyons blue) 



Red 



Yellow 



+ 2.5 

 -!-3 



-4.5 



-4.8 



-7-4 

 -6.9 



-8.9 



In violet light all the larvae died, owing to bacteria. The order 

 of growth for the other colors was: white, blue (copper sul- 

 phate), green, red, blue (Lyons blue), yellow. The order is so 

 different from that given by Yung that, although done on 

 different animals, the interpretation of the real influence of the 

 light is probably open to question. 



Beclard found that the eggs of the fly, Musca carnivora, 

 when reared under different colors developed fastest in violet 

 light and most slowly in green. The sequence for all the colors 

 used is violet, blue, red, yellow, green. This order agrees more 



