A. C. REDFIELD AND E. M. BRIGHT 



257 



ess of membrane formation does not occur until after fertilization. 

 We have found that this process is greatly affected by temperature 

 and have taken care that it should go on at the same temperature in 

 both lots of eggs. Consequently we have avoided the disturbing in- 



10 



too 



20 30 40 60 80 



Fig. 1. Curves illustrating the effect of temperature upon the velocity of the 

 change produced by /3-rays in the membrane of Nereis eggs. Time of radiation 

 in minutes is measured logarithmically along the abscissa. Volumes of mem- 

 branes are measured in 100,000 cubic microns along the ordinate. Intensity of 

 radiation was 38.1 millicurie centimeters in both cases. 



fluence of a secondary reaction analogous to that to which the high 

 temperature coefficient of photosynthesis is attributable.* 



When measurements of the volumes of membranes so produced are 

 plotted against the logarithms of the times of exposure, the points 



