434 



EFFECT OF LIGHT 



[Ch. 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 

 Peecentage Deviations in Length of Larv^ of Steongylooentrotus 



LIVIDUS reared behind VARIOUS COLOEED SCREENS, FROM LENGTH OF 



Larv^ 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 Lj^on's blue), yellow. This series differs so 

 much from Beclaed's that the experiment demands confirmation. 



Certain experiments of Yxjng 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 op Hatching of Organisms reared behind Colored 



Screens 



* Had not hatched by 62 days. 



