HEEEDITY AND SEX 



therefore the smaller gamete, the so-called 

 micro-gamete. 



From the standpoint of metabolism, the 

 female is the more advanced condition; the 

 female performs the larger function, doing all 

 that the male does in furnishing the material 

 basis of heredity (a gamete), and in addition 

 supplying food for the embryo. As regards 

 the reproductive function, the female is the 

 equivalent of the male organism, plus an ad- 

 ditional function, that of supplying the em- 

 bryo with food. When we come to consider the 

 structural basis of sex, we find reasons for 

 thinking that here, too, the female individual 

 is the equivalent of the male plus an addi- 

 tional element. The conclusion has very natu- 

 rally been drawn that if a means could be 

 devised for increasing the nourishment of the 

 egg or embryo, its development into a female 

 should be thereby insured, while the reverse 

 treatment should lead to the production of a 

 male. But in practice this a priori expecta- 

 tion is not fulfilled. Better nourishment of the 

 mother may lead to the production of more 

 eggs, but not of more female offspring, as has 



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