594 APPENDIX A. 



the components of the bdy become the less can they bcr.r 

 separating. And that which thus individuates many parts into 

 one whole, must be considered as more broadly distinguished 

 from the parts individuated, than any of these parts from each 

 other. Further evidence in support of this position may be 

 drawn from the fact, that as we ascend in the scale of animal life, 

 that is, as the co-ordination of actions becomes greater, we find 

 the co-ordinating or nervous system becoming more and more 

 definitely separated from the rest ; and in the vertebrate or 

 highest type of structure we find the division above insisted on 

 distinctly marked. The co-ordinating parts and the parts co- 

 ordinated are placed on opposite sides of the vertebral column. 

 With the exception of a few ganglia, the whole of the nervous 

 masses are contained within the neural arches of the vertebrae ; 

 whilst all the viscera and limbs are contained within, or appended 

 to, the haemal arches the terms neural and haemal having, in- 

 deed, been chosen to express this fundamental division. 



If, then, there be truth in the assumption that the two 

 elements, which, by their union, give origin to a new organism, 

 typify the two essential constituents of such new organism, we 

 must infer that the sperm-cell and germ-cell respectively consist 

 of co-ordinating matter and matter to be co-ordinated neurine 

 and nutriment. That apparent identity of sperm-cell and germ- 

 cell seen in the lowest forms of life may thus be understood as 

 significant to the fact that no extended co-ordination of actions 

 exists in the generative product each cell being a separate indi- 

 vidual ; and the dissimilarity seen in higher organic types may, 

 conversely, be understood as expressive of, and consequent upon, 

 the increasing degree of co-ordination exhibited." * 



That the sperm-cell and germ-cell are thus contrasted in 

 nature and function may further be suspected on considering 

 the distinctive characteristics of the sexes. Of the two elements 

 they respectively contribute to the formation of a fertile germ, it 

 may be reasonabjy supposed that each furnishes that which it 

 possesses in greatest abundance and can best spare. Well, in 

 the greater size of the nervous centres in the male, as well as in 

 the fact that during famines men succumb sooner than women, 

 we see that in the male the co-ordinating system is relatively 

 predominant. From the same evidence, as well as from the 

 greater abundance of the cellular and adipose tissues in women, 

 we may infer that the nutritive system predominates in the 

 female, f Here, then, is additional support for the hypothesis 



* Should it be objected that in the higher plants the sperm cell and germ- 

 cell differ, though no distinct co-ordinating system exists, it is replied that 

 there is co ordination of actions, though of a feeble kind, and that there must 

 be some agency by which this is carried on. 



f It is a significant fact that amongst the diu-cious invertebrata, where the 



