78 THE EGGS OF MAMMALS 



contained either attached sperm or male pronuclei, whereas 

 all ova with single polar bodies showed no signs of sperm 

 entry with the exception of two heavily polyspermic ova. 

 Polyspermy may prevent the second polar division, but 

 probably only when extremely active and dense sperm sus- 

 pensions are used. The presence of two polar bodies may 

 therefore ordinarily be taken as a sign of activation. 



It is evident from the data of Table IX that both the 

 degree and speed of dispersion of the follicle cell mass is 

 roughly proportional to the concentration of the sperm sus- 

 pensions used and that those sperm concentrations which 

 fail to effect a complete dispersion of the follicle cell mass 

 also fail to cause second polar body formation. But rat sperm 

 as well as rabbit sperm can effect complete dispersal of the 

 folhcle cells about rabbit ova and yet no polar body forma- 

 tion occurs. This seems to indicate that the activation of 

 the o\aim and follicle cell dispersion involve distinct and 

 separate reactions. 



The data of Table X substantiate this conclusion for they 

 show that sperm-free fluid from the vas deferens and sperm 

 suspensions heated to 60° C. for a few minutes cause typical 

 follicle cell dispersion but no polar body formation. That a 

 heat-labile substance is involved in the follicle cell disper- 

 sion is evidenced by the data on ova exposed to boiled sperm 

 suspensions. This substance is probably carried by the 

 sperm since similar follicle cell dispersion in vivo is brought 

 about by sperm that have travelled the length of the oviducts. 



Yamane (1930) found that both rat and horse spermatozoa 

 caused second polar body formation in rabbit ova, and since 

 his pancreatin solutions also caused the same result he con- 

 cluded that a non-species-specific sperm-borne tryptase was 

 involved. As shown in Table IX above rat sperm were 

 ineffective in causing second polar body formation, but they 

 were more potent than rabbit sperm suspensions in causing 

 follicle cell dispersion. Accordingly Pincus and Enzmann 

 (1936a) undertook the experiments with trypsin preparations 

 presented in Table XL 



