232 



JACQUES LOEB AND HARDOLPH WASTENEYS 



that if we keep them in the dark before using them they are 

 more sensitive to light and less liable to stick so soon, and such 

 animals gave clearer results. The most efficient part of the spec- 

 trum was situated in the bluish-green in the region of about 

 X = 495 /JL/JL. And finally, experiments with this method on the 

 larvae of Balanus eburneus yielded the result that the most ef- 

 ficient part of the spectrum lies between X = 5(30 and X = 578 mm-'' 



Chlamydomonas pisiformis. Dill. 

 Wave lengths in /xju 



The relative efficiency of the different parts of the carbon arc 

 spectrum for different organisms is plotted in figure 7. The up- 

 per line gives the wave length and below are found the relative 

 efficiency of the various wave lengths as revealed by the two- 

 beams method for Eudendrium ramosum, Euglena viridis, larvae 



^' These results agree with previous observations by Loeb and Maxwell, 

 Univ. Cal. Put)., 1910, Phvsiol., 3, 195. 



