1895.] Organic Variation. 891 
tage over others. Such a difference in original power of 
absorbing nutriment would, perhaps, grow more declared as 
development proceeded, and the several molecular groups 
differentiated into embryo organs. 
If such a competition existed, what would be its natural re- 
sult? Here we have the principle of survival—or, at least, of 
precedence—of the fittest active within the germ itself, and pro- 
ducing an effect on the constitution of the individual. Certain 
organs of the embryo might be better supplied with nutriment 
than others, and, in consequence, become larger or more vitally 
active in the resulting body. And it may be that this differ- 
ence in nutrition would have some influence upon heredity ; 
perhaps the weaker, perhaps the stronger, molecular groups 
being most under control of hereditary influences, and develop- 
ing accordingly. 
If the possibility of such a state of affairs as this be admitted, 
it may aid to explain the peculiarities of variation. Wecould 
understand, for instance, why, in two brothers—even two twin 
brothers—one is more vigorous in this, one in that, organic 
function; one has this weakness, one that. Here the heart 
may be specially strong or weak; here the lungs may be 
specially active; here the muscular, here the nervous, tissues 
may be particularly well-developed; here there may be a 
powerful bodily frame, there a large brain and superior intel- 
lect. Similar variations may occur in the digestive and ex- 
cretory organs, the glandular activity, the deposition of pig- 
ment, and other organic conditions. Or one brother may 
have a general advantage in nutrition over the other, becom- 
ing larger and stronger throughout. Differences in the gen- 
eral form of the body, in its fat-making proclivities, in its 
degree of vital energy, might arise from similar differences in 
powers of assimilation of the molecular groups of the germinal 
cell. 
The above is offered as a suggestion of a conceivable cause 
of organic variations. It, unfortunately, belongs to that wide 
category of hypotheses which are not open to proof. It is not 
the only suggestion that presents itself. Another influence at 
work—perhaps a secondary result of that described—is what 
