40 An Examination of Weismannism. 



minute particles of protoplasmic substance, which are 

 called polar bodies \ These both proceed from the 

 nucleus of the ovum, but are not formed simul- 

 taneously. For the first polar body is really one 

 half of the original nucleus of the cell, and therefore 

 is formed by the first segmentation of this nucleus. 

 The second polar body, on the other hand, is one half 

 of the remaining nucleus, and is similarly formed 

 by the second segmentation. Hence, when both 

 polar bodies have been extruded from the ovum, only 

 one quarter of the original nuclear matter remains. So 

 far, of course, the facts prove too much for Weis- 

 mann's theory, because the theory wants to get rid of 

 only one half of the original nuclear matter before 

 impregnation, if all the nuclear matter be germ-plasm. 

 Therefore Weismann concludes that all the original 

 nuclear matter of the ripe ovum is not germ-plasm, 

 but that only one half of it is so, while the other half — 

 or that half which goes to constitute the first polar 

 body — is idio-plasm-A, which, as we have already 

 seen, the egg-cell shares in common with all other 

 cells. It is merely " ovogenetic " : its function is that 

 of constructing the ovum, qua cell : it has nothing 

 whatever to do with the germ-plasm which the 

 particular cell contains. Therefore, having discharged 

 its function of constructing this cell, it is itself dis- 

 charged from the cell as the first polar body. 



The nucleus of the fully-formed ovum having thus 

 got rid of all its superfluous idio-plasm-A by throwing 

 off the first polar body, is supposed henceforth to 



1 For an account of the formation and expulsion of these bodies, see 

 Part I, pp. 125-6. There is now no longer any doubt touching the 

 statement there made as to the male-cell likewise parting with some of 

 its nuclear substance prior to fertilizing the female. 



