210 
C. Judson Herrick 
ing a little less than 2.5 ounces (64 grams in Macropus rufus, see 
Ziehen in Bardeleben’s Handhuch der Anatomie, 1903), or a ratio 
of brain to body weight of 1 : 711. In the human race this ratio 
is 1 : 42. The average brain weight of European men is about 
three pounds (1353 grams), the brain being 21 times as heavy as 
that of a kangaroo of about the same body weight. This increase 
in the weight of the human brain is almost entirely localized in 
the association centers of the cerebral cortex and structures 
immediately dependent upon them, the old brain remaining on 
practically the same level as in the kangaroo, except for the 
actual reduction in man of some of the simple sensory apparatuses, 
notably the centers for the sense of smell. 
An exhaustive study of all that we know of the evolution of 
animal behavior (including animal intelligence) and of the evolu- 
tion of the brain shows that throughout the history of animal 
development these two processes go hand in hand, viz., the 
development of increasing complexity of the reflex and instinc- 
tive life, with a parallel elaboration of the old brain, and, on the 
other hand, the development of higher intellectual capacity and 
docility, with the elaboration of the new brain, or cerebral cortex 
and other parts directly connected therewith. This relation, we 
may be sure, is no accident. 
Now, our educational systems in general have recognized that 
the child brings into the world no mental endowments ready- 
made — no knowledge, no ideas, no morals. These have to be 
developed anew in each generation under the guiding hand of 
education, for they are the functions of those association centers 
whose nervous pattern is not fully laid down at birth, but must be 
elaborated slowly during the plastic growing years by personal 
experience. This lesson we have learned and learned so well 
that we devote one-third of the average span of life of our most 
promising youth to the educational training necessary to ensure 
the highest possible development of the latent cultural capaci- 
ties of these association centers of the cerebral cortex. 
But we, as educators, have too often been blind to the further 
fact that the child brings something with him into the world in 
addition to the unformed plastic materials of his association 
centers, viz., an immense capital of preformed and innate ability, 
which takes the form of physiological vigor and instinctive and 
impulsive actions, performed for the most part automatically 
