1884) The Theory of Sex and Sexual Genesis: 671 
1880). On the other hand, sperm-cells are among the smallest 
cells of the producing organism. Mature germ-cells result from 
the extraordinary growth without division, of certain of the prim- 
itive germinal cells of the ovary, generally with the aid of the 
formative activity of other smaller cells by which they are sur- 
rounded. In animals “the spermatozoa are formed by the break- 
ing up of the male germinal cells, or of cells secondarily derived 
from them by division. The cells which directly give rise by 
division to the spermatozoa may be called spermospores, and are 
equivalent to the ova or odspores” (Balfour, Comp. Embryol., Vol. 
LP. 53). Pollen-grains in like manner are produced by the sub- 
ision of a mother-cell. In all except “the lowest forms of 
vegetable life * * * the two cells that take part in the act 
of sexual union * * # are strikingly different in size, form 
and physical properties. In these cases one of the two cells, the 
_ male cell, conveys to the other only a small quantity of material 
by means of which it produces an effect upon it; this other cell, 
the female cell, contains by far the largest proportion of the ma- 
_ terial which takes part in the development incited by the act of 
_ tion” (Sachs, Botany, p. 224). 
j Thus in the production of germ-cells there is evidently a rela- 
Wve preponderance of the factor of growth; and in the produc- 
_ fon of sperm-cells there is a relative preponderance of that fac- 
: tor of the developmental process which is more especially con- 
_ “emed in cell division. 
-We have next to inquire why this relation or differentiation be- 
: tween the two kinds of cells should be necessary to their codper- 
i ation in the initiation of a complex development. 
___Agerminal aggregate which is fitted to initiate the develop- 
: ent Of a complex organism must be an aggregate of considera- 
: ble size, in order that it may afford an adequate basis for the in- 
w formation of the different parts. The production of such 
i aggregate can only take place on condition of the absence of 
tendency in it to undergo segmentation, and thus enter upon 
Sevelopmental changes while it is yet small. It must be so con- 
end and So placed that there is a relative deficiency of the 
~or Of cell-division in the formative processes by which it is 
“oe, hen, When it has attained the requisite size, it is 
wis. ifitted for active development until this deficiency is sup- 
: and the proper’balance between the two factors is restored. 
