The Foundations of Culture 
209 
the members of a given child population^ still more variety is 
introduced into the problem by the fact that all truly intellectual 
attainment^ as distinguished from the innate instinctive pattern^ 
must be individually acquired, and its character will depend 
wholly upon the personal experience of the child himself and the 
nature of the environment within which this experience must 
be gained. 
The structural basis of this three-fold inheritance is very 
plainly seen in (1) bodily configuration; (2) the inherited form of 
brain and its internal web of nerve cells and fibers, which provide 
a fixed mechanism, common except for minor variations to all 
members of the race alike, for the performance of their common 
instinctive actions; and (3) the large association centers of the 
brain, the exact form of whose internal organization is not wholly 
predetermined at birth, but is shaped for each individual sepa- 
rately during the course of his growth period by the process of 
education to which he is subjected. 
This third element is by no means a new structure in the human 
brain. It has been my task for many years past to study the 
evolutionary history and primeval sources of these correlation 
centers as they are found in the lower animals. It is found that 
this tissue is present in all lower vertebrates and that its amount 
is directly proportional to the intellectual capacities and docility 
of the animals exhibiting it. In the nobler species of animals 
and in man it does not replace the lower reflex and instinctive 
mechanisms, but it is superposed upon these. None of these 
higher associational (intellectual) activities are possible, except 
through the mediation of the lower or instinctive centers. Neu- 
rologists, accordingly, now distinguish an old brain (palaeen- 
cephalon), which is common to all members of the vertebrate 
branch of the animal kingdom, from a new brain (neencephalon), 
which is practically coextensive with the cerebral cortex. The 
new brain, with its functions of correlation, is really as old, so 
far as its first beginnings are concerned, as the old brain; but, 
whereas the latter attains its full development as a reflex and 
instinctive apparatus in the lowest mammals, the former con- 
tinues to increase in size and importance and it is still increasing 
in the civilized human races today. 
The kangaroo is one of the lowest types of mammals. A kan- 
garoo with a body weight of about 100 pounds has a brain weigh- 
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