540 The American Naturalist. [July, 
transmission seems to be mainly useful as enabling a species 
to get instincts slowly in determinate directions, by keeping 
off the operation of natural selection. Social Heredity is then 
the lesser factor ; it serves Biological Heredity. Butin man, the 
reverse. Social transmission is the important factor, and the 
congenital equipment of instincts is actually broken up in 
order to allow the plasticity which the human being’s social 
learning requires him to have. So in all cases both factors are 
present, but in a sort of inverse ratio to each other. In the 
words of Preyer, “ the more kinds of co-ordinated movement an 
animal brings into the world, the fewer is he able to learn 
afterwards.” The child is the animal which inherits the 
smallest number of congenital co-ordinations, but he is the one 
that learns the greatest number (ref. 2, p. 297). 
“It is very probable, as far as the early life of the child may 
be taken as indicating the factors of evolution, that the main 
function of consciousness is to enable him to learn things which 
natural heredity fails to transmit; and with the child the fact 
that consciousness is the essential means of all his learning is 
correlated with the other fact that the child is the very crea- 
ture for which natural heredity gives few independent func- 
tions. It is in this field only that I venture to speak with 
assurance; but the same point of view has been reached by 
Weismann and others on the purely biological side. The in- 
stinctive equipment of the lower animals is replaced by the 
plasticity for learning by consciousness. So it seems to me 
that the evidence points to some inverse ratio between the im- 
portance of consciousness as factor in development and the 
need of inheritance of acquired characters as factor in develop- 
ment ” (ref. 7). 
“ Under this general conception we may bring the biological 
phenomena of infancy, with all their evolutionary significance : 
the great plasticity of the mammal infant as opposed to the 
highly developed instinctive equipment of other young; the 
maternal care, instruction and example during the period of 
dependence, and the very gradual attainment of the activities 
of self-maintenance in conditions in which social activities are 
absolutely essential. All this stock of the development theory 
is available to confirm this view ” (Ref. 3). 
