606 PROFESSOR MARCUS IIARTOG. 



C. — The Role of the Sperm. 



This has been a matter of mucli debate. One school sees 

 in it merely the bearing-in of the ferment that starts* the 

 oosperm into development, or of a new centrosome to the 

 oosphere which has lost its own during the formation of the 

 polar bodies. Another school refuses to consider anything 

 but the male nucleus, which indeed constitutes the bulk of 

 the sperm at its entrance. Others, again, insist that however 

 small be the cytoplasm of the sperm in quantity, it is by no 

 means negligible in quality. A consideration of the facts as 

 presented in Nature, and described and figured concordantly 

 by numerous trustworthy observers, will convince us that the 

 third view is a decided under-statement of the case. 



The minute size of the sperm with its bare envelope of 

 cytoplasm are correlated with the presence of large stores of 

 unorganised reserves in the egg. When it enters, its nucleus 

 is so concentrated and condensed that it cannot fuse with the 

 female nucleus until it has attained a more normal condition, 

 and for this it must be nourished. 



The first function, therefore^ of the sperm on entering the 

 egg is to procure this nourishment for itself, which it does b}' 

 digesting some of the reserve of the egg; whereupon the cj^to- 

 plasm of the sperm with its centrosome grows even more 

 rapidly than its nucleus, till the organised living matter of the 

 oosperm is seen to be largely constituted by this growth of 

 the male clement. This is clearly shown in the exquisite 

 figures oP Wilson (1) (Echinoderms) and Vejdovsky (2) (Oligo- 

 chaetes). 



Now we must insist that the yolk-granules are not living 

 matter at all, but mere inclusions within the living cell, 

 absolutely comparable to starch granules. The nature of pro- 

 toplasm is not determined by its food, but by its origin, so that 

 the fact that the male cytoplasm grows in this way within the 

 eo-jr does not lessen its essential maleness. 



Complete conjugation only takes place, we may say, with 



