SPERM FILTRATES AND DIM A/Ml s. 



321 



produced decided changes in ova of both species of Strongylo- 

 centrottis. 



c. Nereis limbata. Sperm filtrates of Nereis limbata produce 

 effects on ova of this species comparable to those produced by 

 foreign sperm filtrates. An exposure of Nereis eggs to filtrates 



VQ 



fco 



fo 



o 



JC 



40 



lo 



E. T I 



10 



GRAPH XI. GRAPH XII. 



The effect on ova of Arbacia of limited exposure to filtrates. 



Filtrate of a 2 Per Filtrate of a 2 Per 



Cent. Suspension. Cent. Suspension. 



A sea-water 10 hrs. A = sea- water 10 hrs. 

 = filtrate is"-4S" = nitrate is"-45" 



B = " 75" B = " 210" 



C = 135" C = 4.5 hrs. 



D = " 195" Z? = 9 hrs. 



E = 9 hrs. 



The percentages of ova divided and cytolyzed are indicated. 



made from one, two or ten per cent. Nereis sperm suspensions 

 results in the formation of jelly and fertilization membranes and 

 the complete maturation of a certain percentage of eggs. The 

 most satisfactory results were obtained with eggs transferred 

 directly to a two per cent, filtrate, and within two hours after 



