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ALVALYN E. WOODWARD 



the fertilization membrane. Practically the same thing occurred 

 in the case of Arbacia, with the exception that no fertilization 

 membrane was formed, and only the jelly surrounding the egg 

 held the fragments together for a time. This soon broke up, 

 however, and allowed the larvae to escape. The irregularity of 

 cleavage was less marked in the eggs which had not been sub- 

 jected to hypertonic after-treatment, but, on the other hand, 

 the eggs with the hypertonic after-treatment gave a larger per- 



centage of swimming larvae. That is, these eggs developed 

 farther than those treated with fertilizin alone. 



While autoparthenogenesis must be considered in formulating 

 any general theory of fertilization, it is also of immediate practical 

 value in our analysis of the egg secretion, which is thus shown to 

 affect both egg and sperm. This indication that the secretion 

 may have at least a dual nature is strengthened by other observa- 

 tions: 1) Boiling does not destroy its power to agglutinate sperm 

 (Lillie), but does destroy its value as a parthenogenetic agent 

 (Glaser). 2) Arbacia blood inhibits sperm fertilization, but does 

 not affect the agglutinating power of the secretion (Lillie); 



