Later Additions zip to the year 1892. 43 



the offspring of the same parents do not all precisely 

 resemble one another. These, be it observed, are the 

 only two functions which Weismann's theory of polar 

 bodies subserves in relation to his theory of germ-plasm. 

 But, it appears to me, neither of these functions is 

 necessary, in so far as any requirements of the latter 

 theory are concerned. For surely, polar bodies or no 

 polar bodies, there is already a mechanism at work in 

 each ontogeny which is of itself sufficient to discharge 

 both these functions, and so to anticipate both the 

 supposed difficulties which the subsidiary theory is 

 adduced to meet. The very essence of ontogeny, 

 as a process, itself consists in a continuous succession 

 of nuclear divisions — and this not only as regards 

 somatic-cells, but also as regards germ-cells. Now, in 

 the great majority of organisms, there is an infinitely 

 greater number of germ cells (both male and female) 

 than can possibly be required either for the purpose 

 of getting rid of any excess of germ-plasms in the 

 nucleus of each cell, or of preventing the germ-plasms 

 of any one germ-cell precisely resembling those of 

 any other. If every plant or animal produced only 

 a single female-cell or a single male-cell, then indeed 

 we might require from Professor Weismann a demon- 

 stration of some special mechanism to secure the ex- 

 pulsion of half its ancestral germ-plasms ; since other- 

 wise the single female-cell or male-cell would have to 

 increase its dimensions in each successive generation. 

 But. as matters actually stand, nature seems to have 

 made much more than ample provision for prevent- 

 ing the undue accumulation of ancestral germ-plasms 

 in any individual germ-cell, by enormously multiply- 

 ing, through continuous division and subdivision, the 



