366 
And clearly such a contention is a perfectly logical one. 
For the object of selection is to secure the marriage of 
similar variants ; but if all vary in the same way, it is 
obvious that the most promiscuous marriage will suffice 
to reproduce the variations common to both parents. 
What Mr. Darwin says of the direct action of changed 
conditions must, according to the logic of the theory, 
be true also of the effect produced through the sexual 
elements. 
“ There can be little doubt that the tendency to vary in the same 
manner has often been so strong that all the individuals of the 
same species have been similarly modified without the aid of any 
form of selection.”—{Origin of Species, p. 72.) 
“ When any deviation in structure or constitution is common to 
both parents, this is often transmitted in an augmented degree to the 
offspring.”—(Origin of Species, p. 257.) 
Some years back, Mr. Francis Galton published in the 
Contemporary Review,* an article entitled “ A Theory of 
Heredity,” which has often been credited with anticipating 
the theory of Dr. Weismann, and is, I believe, generally 
regarded as favourable to the doctrine of Natural Selec 
tion. In this Essay, he designates “the sum total of the 
contents of the newly fertilised ovum,” by the term “stirp” 
{stirpes = a root). He asserts that the stirp contains a 
much greater number of germs than achieve development 
in the body of the individual. These residual germs 
retain their vitality, and contribute to form the stirp of 
the descendants. As fertility resides somewhere, it must 
have been vested in the non-developed residue of the 
stirp, or rather in its progeny and representatives (what 
ever, or however numerous, they may be) at the time 
when the individual has reached adult life. Mr. Galton 
Vol. xxvii., pp. 80-95.