214 THE CONTINUITY OF THE GERM-PLASM AS THE 



body, or, in other words, in order that embryonic development 

 may beg-in, the still preponderating- ovogenetic nucleoplasm must 

 be removed from the cell. This removal takes place in the same 

 manner as that in which differing 1 nuclear substances are separated 

 during 1 the ontogeny of the embryo : viz. by nuclear division, 

 leading to cell-division. The expulsion of the polar bodies is 

 nothing more than the. removal of ovogenetic nucleoplasm from 

 the egg-cell. That the ovogenetic nucleoplasm continues to 

 greatly preponderate in the nucleus up to the very last, may be 

 concluded from the fact that two successive divisions of the latter 

 and the expulsion of two polar bodies appear to be the rule. If in 

 this way a small part of the cell-body is expelled from the egg, 

 the extrusion must in all probability be considered as an inevitable 

 loss, without which the removal of the ovogenetic nucleoplasm 

 cannot be effected. 



This is my theory of the significance of polar bodies, and I 

 do not intend to contrast it, in extenso, with the theories pro- 

 pounded by others ; for such theories are well known and differ 

 essentially from my own. All writers agree in supposing that 

 something which would be an obstacle to embiyonic development 

 is removed from the egg ; but opinions differ as to the nature of 

 this substance and the precise reasons for its removal l . Some ob- 

 servers (e. g. Minot 2 , van Beneden, and Balfour) regard the 

 nucleus as hermaphrodite, and assume that in the polar bodies the 

 male element is expelled in order to render the egg capable of 

 fertilization. Others speak of a rejuvenescence of the nucleus, 

 others again believe that the quantity of nuclear substance must be 

 reduced in order to become equal to that of the generally minute 

 sperm-nucleus, and that the proportions for nuclear conjugation are 

 in this way adjusted. 



The first view seems to me to be disproved by the fact that male 

 as well as female qualities are transmitted by the egg-cell, while 

 the sperm-cell also transmits female qualities. The germ-plasm of 

 the nucleus of the egg cannot therefore be considered as female, 



1 Thus in 1877 Bfltsclili thought that 'the chief significance of the formation of 

 polar bodies lies in the removal of part of the nucleus of the egg, whether this 

 removal is effected by simple expulsion or by the budding of the egg-cell.' ' Ent- 

 wicklungsgeschichtliche Beitrage ; ' Zeitachrift fiir wissenschaftliche Zoologie, Bd. 

 XXIX. p. 237, footnote. 



* C. 8. Minot, ' Account, etc.;' Proc. Boston Soc. Nat. Hist. vol. xix. p. 165, 1877. 



