^i'll ON THE NUMBER OF POLAR BODIES AND [VI. 



as I have already argued, two successive divisions of the num- 

 ber of ancestral germ-plasms into halves is inconceivable ; and 

 because the first polar body is also present in parthenogenetic 

 eggs in which such division into halves cannot take place. 

 But the karyokinetic process can readily be looked upon as 

 a removal of ovogenetic nucleoplasm, for we know from the 

 observations of Flemming and Carnoy, that, under certain 

 circumstances, subsequent divisions may occur, involving an 

 increase in the number of nuclear loops to double their num- 

 ber. These subsequent divisions of course take place in the 

 daughter-nuclei. This fact proves, as I think, that there are 

 nuclei in which the same ancestral germ-plasm occurs in two 

 different loops : but such loops, identical as regards the com- 

 position of their ancestral germ-plasms, may very well contain 

 different ontogenetic stages of this substance. This will be the 

 case in the instance alluded to, if four loops of the first nuclear 

 spindle are to be looked upon as ovogenetic nucleoplasm, and 

 the four others as germ-plasm. It is therefore unnecessary 

 to regard the first division of the egg-nucleus as a ' reducing 

 division ' : it may be looked upon as an * equal division ' ^ en- 

 tirely analogous to the kind of division which, in my opinion, 

 directs the developm.ent of the embryo. This conclusion would 

 receive direct proof if it were possible to show that the eight 

 loops of the first division have arisen by the longitudinal 

 splitting of four primary loops : for a longitudinal splitting of 

 the nuclear thread would be the means by which the different 

 ontogenetic stages of the germ-plasm could be separated from 

 one another, without leading to any reduction in the number of 

 ancestral germ-plasms in the daughter-nuclei. Thus I have 

 previously attempted to prove that the ontogenetic development 

 of the ^gg must be connected with a progressive transformation 

 of the nucleoplasm during successive nuclear divisions, and this 

 transformation will very frequently (but not always) occur in 

 such a way that the different qualities of the nucleoplasm are 

 separated from one another by the nuclear division. The nu- 

 cleoplasm of the daughter-nuclei will be identical if the two 

 daughter-cells are to potentially contain corresponding parts of 

 the embryo ; as for instance the first two segmentation spheres 



1 See p. 375. 



