136 FOOT-NOTES TO EVOLUTION. 



life comes from such sources outside the germ cell and 

 outside of heredity. All powers may be affected by it. 

 Perfect development demands the highest nutrition, an 

 ideal never reached. In such fashion 

 ' sts> the child may bear the incubus of Ibsen's 

 " Ghosts " for which it had no personal responsibility. 

 " Spent passions and vanished sins " may impair germ 

 cells, male or female, as they injure the organs that pro- 

 duce them. We must then represent the perfection of 

 transmission by T, and T is a fraction, large or small, 

 but always less than unity. It would stand as a re- 

 ducing agency, and as such in algebra it would be best 

 represented as a divisor. The whole formula may be 



multiplied by rp, a process that, like the process Z, 



which if it exists is an extension of T, must intervene 



between conception and birth. 



This formula indicates simply the possibilities of 



Richard Roe as the sexless embryo, the joined proto- 

 plasm and united chromatin of the two 



Determination ,, TI,- u 



parent germ cells. 1ms germ has now 



to grow and expand by cell division. 

 But besides its vegetative growth two possible lines of 

 development lie before it, one of which it must take. It 

 must assume sex. It must become either male or female. 

 The choice of the one at the critical time is as feasible as 

 that of the other. But once made the choice is irrevoc- 

 able. Thus far man has found no way to control this 

 choice and Nature makes it for him. The sexless embryo 

 is, as it were, suspended on a hair, to be turned to male or 

 female by the first stimulus which may reach it. In the 

 human race, such impulses must come through the moth- 

 er. Certain of these forces have been partially defined. 

 It has long been known that with certain insects and 

 crustaceans full nutrition increases the number of fe- 



