34 Mary Blount. 



necessary for "die harmonisclie Weiterentwickelung des befruchteten 

 Eies." And Henking is satisfied that both the monospermic and 

 polyspermic eggs proceed to normal development. 



Riickert has suggested that perhaps the merocyte nuclei favor 

 the division of the marginal blastomeres. In the pigeon, the primary- 

 cleavage in early stages is far from what we must suppose to be the 

 sphere of influence of the supernumerary nuclei. It is not until after 

 the disappearance of the latter that there is much division of the 

 marginal blastomeres, 



A nutritive function has often been assigned to these nuclei, 

 as if they digest the yolk and pass the products on to the developing 



Fig. 15. — A nucleus derived fi'om one of the supernumerary spermatozoa, and 

 its surroundings. This is the more central of the two nuclei at the right-hand 

 side of Fig. 2. sn., sperm nucleus, vit., vitelline membrane, y, yolk gran- 

 ules showing signs of digestion. Leitz 4/i\. Tube length 140 mm. 



germ. Fig. 15 shows a sperm nucleus in a maturation stage (one 

 of the nuclei in Fig. 2). It seems to be digesting the yolk around 

 it. Riickert insists that even if they do degenerate later, they may 

 be indispensable for nutrition in the early stages. I cannot prove 

 that they do not function in this way. However, since the entrance 

 of the supernumerary spermatozoa into the egg is more or less a 

 matter of chance (in the sense that anything can be chance) and 

 since their number varies, I cannot believe that their presence is 

 essential to normal development. I believe that if but one spermato- 

 zoon entered the pigeon's egg, normal development might ensue. 



