224 COXTINUITY OF THE GERM-PLASM AS THE [IV. 



It is true that we cannot say a priori whether the influence 

 exercised on the sperm-cell by the spermogenetic nucleoplasm 

 might not be eliminated by some means other than its removal 

 from the cell. It is conceivable, for instance, that this sub- 

 stance may be expelled from the nucleus, but may remain in 

 the cell-body, where it is in some way rendered powerless. We 

 do not yet really know anything of the essential conditions of 

 nuclear division, and it is quite impossible to bring forward any 

 facts in support of my previous suggestion. The germ-plasm 

 is supposed to be present in the nucleus of the growing egg-cell 

 in smaller quantity than the ovogenetic nucleoplasm, and the 

 germ-plasm gradually increases in quantity : thus when the ^g^ 

 has attained its maximum size, the opposition between the two 

 different kinds of nucleoplasm becomes so marked, in conse- 

 quence of the alteration in their quantitative relations, that their 

 separation, viz. nuclear division, results. But although we are 

 not able to distinguish, by any visible characteristics, the dif- 

 ferent 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 ovo- 

 genetic 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 quantity. For obviously these two kinds of 

 nucleoplasm exert opposite tendencies in at least one respect. 

 The germ-plasm tends to effect the division of the cell into the 

 first two 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 nucleo- 

 plasm until it has reached such a relative size as enables it to 

 successfully oppose the latter. 



