THE CONTINUITY OF THE GERM-PLASM AS THE 



although we are not able to distinguish, by any visible charac- 

 teristics, the different kinds of nucleoplasm which may be united 

 in one nuclear thread, the assumption that the influence of each 

 kind bears a direct proportion to its quantity is the most obvious 

 and natural one. The tendency of the germ-plasm contained 

 in the nucleus cannot make itself felt so long as an excess of 

 ovogenetic nucleoplasm is also present. We may imagine that 

 the effects of the two different kinds of nucleoplasm are combined 

 to produce a resultant effect ; but when the two influences exerted 

 upon the cell are nearly opposed, only the stronger can make 

 itself felt, and in such a case the latter must exceed the former in 

 quantity, because part of it is as it were neutralized by the other 

 nucleoplasm working in an opposite direction. This metaphorical 

 representation may give us a clue to explain the fact that the 

 ovogenetic nucleoplasm comes to exceed the germ-plasm in quan- 

 tity. For obviously these two kinds of nucleoplasm exert oppo- 

 site tendencies in at least one respect. The germ-plasm tends 

 to effect the division of the cell into the 'two first segmentation 

 spheres ; the ovogenetic nucleoplasm, on the other hand, possesses a 

 tendency towards the growth of the cell-body without division. 

 Hence the germ-plasm cannot make itself felt, and is not able to 

 expel the ovogenetic nucleoplasm until it has reached such a 

 relative size as enables it to successfully oppose the latter. 



Applying these ideas to the sperm-cells we must see whether 

 the expulsion of part of the nuclear substance, viz. of the sperm o- 

 genetic nucleoplasm, corresponding to the ovogenetic nucleoplasm, 

 takes place in them also. 



As far as we can judge from thoroughly substantiated obser- 

 vations such phenomena are indeed found in many cases, although 

 they appear to be different from those occurring in the egg-cell, 

 and cannot receive quite so certain an interpretation. 



The attempt to prove that a process similar to the expulsion of 

 polar bodies takes place in the formation of sperm-cells has already 

 been made by those observers who regard such expulsion as the 

 removal of the male element from the egg, thus leading to sexual 

 differentiation ; for such a theory also requires the removal of part 

 of the nuclear substance from the maturing sperm-cell. Thus, 

 according to E. van Beneden and Ch. Julin, the cells which, in 

 Mcaris, produce the spermatogouia (mother-cells of the sperm-cells). 



