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 
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 
Ibsen’s Ghosts. 
multiplied by 7 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 
parent germ cells. This 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 makesit 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- 
Determination 
of sex. 
