THEORY OF SEX-DIMORPHISM 95 



there is the beginning of a yolk-gland an 

 advantageous addition obviously. In the 

 course of time the organism reproduces and 

 its germ-cells have entailed on them (in 

 accordance with the conception of germinal 

 continuity) the primary constituent (deter- 

 minant or factor) of a yolk-gland. But the 

 difficulty immediately arises in the mind that 

 this new hereditary item will be found not 

 only in the germ-cells which will develop 

 into females (where it will be relevant), but 

 also in the germ-cells which will develop into 

 males (where it will be irrelevant). The ques- 

 tion, then, is what will happen to the yolk- 

 gland determinant in those germ -cells that 

 are going to develop into males. The answer 

 is that it will remain latent, not because its 

 expression would be irrelevant, but because 

 it arose as a variation in a germ-cell pre- 

 disposed to develop into a female. It is 

 solidary with femaleness, which, for us. means 

 a metabolism-ratio or rhythm with relatively 

 preponderant anabolism. Metaphorically, it 

 is a seed which will germinate in female soil, 

 which will not germinate in male soil, though 

 it will remain latent there. 



For the sake of clearness, let us take the 

 same occurrence on the male side. In a 

 germ-cell (whether ovum or spermatozoon, 

 or fertilised ovum), predisposed to develop 

 into a male i.e. a sperm-producer, a variation 

 arises, say, in the direction of brilliant pig- 

 mentation of the skin. If it is consistent with 

 the rest of the organisation, it is realised in 

 development, the spermatozoa have it en- 

 tailed on them, and it is transferred to a 



