M'l KM 111 IK Nil-- \\|) hi \|.V/ VI KS. 



309 



semination with Nereis sperm. The foreign filtrate causes pro- 

 duction of jelly, the formation of a "fertilization membrane," 

 complete maturation, and segmentation leading to the develop- 

 ment of larvae. 2 The latter however are abnormal in shape and 

 in the distribution of cilia. In no case did these changes occur 

 in sea-water controls. A protocol of one experiment is given 

 below. 



TABLE I. 



CHANGES IN THE OVA OF Nereis EXPOSED FOR TWENTY MINUTES TO A FILTRATE 

 PREPARED FROM A Two PER CENT. SPERM SUSPENSION OF Arbacia. 



In experiments 31, 40, and 43 the ova were stale. In all cases 

 membrane formation and maturation occurred as rapidly in ova 

 in sperm filtrates as in inseminated ova. Subsequent develop- 

 ment in ova treated with filtrate was delayed. 



The Arbacia sperm filtrate acted like a parthenogenetic agent, 

 yielding results similar to those obtained in Nereis with other 

 methods (Lillie, 1911, and Just, I9I5). 2 I obtained similar 

 results with filtered egg-water of Arbacia. The latter observa- 

 tions, quoted by Dr. Alvalyn Woodward (1921), were verified 

 frequently in subsequent experiments. Further experimentation 

 demonstrated that the effect produced by sperm filtrates on 

 Nereis eggs bears a definite relation to the strength of the prepa- 

 rations and to the duration of exposure of ova to them. The 

 main question however is what effect have such filtrates and 

 dialyzates on ova of the same species. 



1 The developing ova divided into two. four and eight cells, and subsequently 

 some of them developed into abnormal ciliated trochophores. The rest cytolyzed. 



