ULTRAVIOLET AND ARBACIA FERTILIZATION. 



423 



crease in acidity was noted. Following adsorption of the colloid 

 components of egg-- water by charcoal, an increase in alkalinity 

 occurred. 



FIG. i. Normal decline of agglutinating power of a sample of non- 

 radiated egg-water. Ordinates, agglutinating units. Abscissae, duration of 

 experiment, in days. 



Charcoal Adsorption. Equal weights of animal charcoal, previ- 

 ously washed and dried, were added to equal quantities of a series 

 of dilutions of egg-water whose agglutinating power was known. 

 The charcoal egg-water mixture was shaken and then filtered 

 through filter-paper, and its agglutinating power again tested 

 against the same sperm suspension. The filtrate was colorless, 

 and had lost from 90 to 100 per cent, of its agglutinating power, 

 indicating a high adsorption coefficient. (See Table VI. ) Both 

 echinochrome and fertilizin had been adsorbed. (In this connec- 

 tion see also Glaser, '21 a.) 



It will be seen that relatively more fertilizin is adsorbed from 

 samples of egg- water which have been diluted. The data for the 



