1884] Growth, its Conditions and Variations. 1221 
the field of life and diminish the average supply of food. This 
is, as yet, obviated by the augmentation of the food supply 
through human labor, which has, for a long period, caused a 
steadily increasing ratio of food to consumers. Thus the increase 
both of leisure and of food supply of civilized man favors an in- 
creased growth vigor. If in the future of civilization human 
_ fecundity should decrease, as it shows some indications of doing, 
the size and length of life of man might markedly increase, and 
_ the development of the individual gain upon the reproduction of 
race. 
Hereditary influences act strongly to prevent deviation from any 
established: standard. Yet the leveling effects of heredity are 
constantly opposed by energies of variation, These seem to be 
_ of two kinds, variation by the preservation of minute increments, 
= and by considerable leaps of change. The Darwinian theory of 
Specific variation trusts solely to the former, yet the opposing 
_ facts it has to overcome are so many and vigorous, and the pale- 
‘ ontological evidence is so strongly in favor of considerable varia- 
tions, that the idea of leaps from species to species is steadily 
_ §aining strength. , 
: The same considerations hold in’ regard to size variation. It 
! aiy arise from minute changes, or from the preservation of con- 
_ Siderable leaps, Slight variations in size are universal, but leaps 
© giant or dwarf individuals are not uncommon. With the 
; lower animals it is quite possible that these great er ae 
_ “ze, when in harmony. with suddenly changed surrounding con- 
_ ditions, may have been occasionally hereditarily preserved, and 
pid growth or diminution in bulk of a tribe of animals have taken 
1 place. In man such abnormal variations can scarcely become dom 
: oe Human agency has so succeeded in equalizing the ne 
= Supply, and in restraining the tendency of outer nature ja "r 
a ton, that conditions vigorously aiding the preservation of a giant 
oe race are unlikely to arise. The mental force of eee 
: Salso more strongly active against such a change in man ege ae 
lower animals, Thus human variation in size is more si pi 
` in accordance with the Darwinian law, of panee 
ation with slowly varymg 
the exertion necessary to 
ant and dwarf races at 
h, probably produced 
ons, alike in the food supply, the 
nit, and the reproductive energy. Gi 
ent exist in certain regions of the eart 
