484 



EFFECT OF LIGHT 



[Cn. XVII 



Upon Echinoderm larvae VERNON ('95) has made some 

 important experiments. He used YUNG'S methods of getting 

 colors ; but relative intensity is not indicated. The following 

 table gives his results : 



TABLE XLIII 



PERCENTAGE DEVIATIONS IN LENGTH OF LARVAE OF STRONG YLOCENTROTUS 

 LIVIDUS REARED BEHIND VARIOUS COLORED SCREENS, FROM LENGTH OF 

 LARVJE REARED IN WHITE LIGHT 



All larvae reared in violet light soon died on account of the 

 development of bacteria. In this case the order of growth 

 followed the series : white, blue (of copper sulphate solution), 

 green, red, blue (of Lyon's blue), yellow. This series differs so 

 much from BECLABD'S that the experiment demands confirmation. 



Certain experiments of YUNG on the relative time of hatch- 

 ing may be given here, since the time of hatching depends 

 upon rate of growth : 



TABLE XLIV 



RELATIVE TIME OF HATCHING OF ORGANISMS REARED BEHIND COLORED 



SCREENS 



* Had not hatched by 62 days. 



