ULTRAVIOLET AND ARBACIA FERTILIZATION. 



425 



substance to stimulate the sperm to activity. The activating com- 

 ponent of egg- water appears not to be adsorbed by charcoal, or 

 less so than the agglutinating component. 



A. V. 

 too 



300 



200 



100 



B 



C 01 c * t r& t/ Oft. 



FIG. 2. Adsorption of fertilizin on charcoal. Ordinates, agglutinating 

 units. Abscissae, concentration of egg-water used. A. U., agglutinating 

 units. A, agglutinating units in sample before adsorption. B, agglutinating 

 units in sample after adsorption. C, agglutinating units adsorbed. 



When a few drops of concentrated sperm are added to egg- 

 water containing a small amount of charcoal, the sperm immedi- 

 ately attack the bits of charcoal and rotate them about much as 



