PRESIDENTIAL ADDRESS. 593 
essential to Man, which his ancestors retained when those of the giant Anthro- 
poids chose the lesser part of relying upon their strength rather than their 
intelligence. 
From the study of the brain in a series of Apes the fact emerges that in this 
progression there was taking place in the cerebral cortex a gradual extension and 
development of certain areas, which eventually made it possible for the Ape that 
achieved most in this way to make a fuller use of its erect attitude and employ 
its liberated hands and arms for a higher purpose than the rest of its tribe. 
Even in the lowliest Catarrhine Apes the cortical area which is set apart 
directly to receive visual impressions is as large and as highly developed as it ever 
will be; and perhaps we may assume, though our evidence is not yet so satis- 
factory, that the tactile and acoustic areas are not very much inferior, so far as 
the mere perception of touch and hearing is concerned, to those of Man. But 
in the series of Primates we can detect fringes of cortex surrounding, perhaps 
growing out from, these great sensory areas, and others linking these fringing 
bands the one to the other, which show a progressive increase in size and 
complexity of structure, as we proceed from Prosimian to Platyrrhine, Platyr- 
rhine to Catarrhine Ape, and through the series Gibbon, Chimpanzee, and 
Gorilla. 
The progressive increase in size of these aréas presumably connotes the growth 
and perfecting of the apparatus for recording sensory impressions and the com- 
plex states of consciousness which are awakened by the blending of various 
impressions, visual, acoustic, tactile, and the rest, and the memories of similar 
or contrasted forms of consciousness that the individual may have experienced in 
the past. 
In Sir Edward Tylor’s classical book on ‘ Anthropology’ there is an admir- 
able illustration of this in his comparison of the action of children and monkeys 
scrambling for nuts. ‘Knowing a nut by sight, or having an idea of a nut, means 
that there are grouped together in the child’s mind memories of a number of past 
sensations, which have so become connected by experience that a particular form 
and colour, feel and weight, lead to the expectation of a particular flavour. 
Of what here takes place in the child’s mind we can judge, though by no means 
clearly, from what we know about our own thoughts and what others have told 
us about theirs. What takes place in the monkeys’ minds we can only guess 
-by watching their actions, but these are so like the human as to be most readily 
explained by considering their brain-work also to be like the human, though less 
clear and perfect.’ 
In Man there is relatively an enormous increase in the extent and degree of 
differentiation of the (temporo-parietal) region of the cerebral cortex which we 
must associate with this particular category of function. Presumably this 
implies not only that there is provided in the human brain a much more exten- 
sive cortical area in which the records of experience can become imprinted, but 
also that this larger territory will be free from the disturbance of the constant 
traffic upon the main great sensory avenues, such as is inevitable in brains in 
which the temporo-parietal area is little more than a narrow strip sandwiched in 
between the great sensory areas, and liable to be flooded and overwhelmed by 
the sensory impressions streaming into the cortex through them. In the Apes, 
even the most highly endowed Anthropoids, the conduct of the animal is attuned 
to the sensory impressions of the moment (modified in some degree only by the 
experience of the past), because the cerebral cortex is so flooded with impressions 
from the outside world. 
But the time comes in the gradual development of the brain, along the lines 
we see exemplified in the series of Apes, when those cortical areas not imme- 
diately concerned with the reception of sensory impressions become so large and 
so stored with the fruits of experience that they come to exercise an influence 
upon conduct more potent than that of direct sensory stimulation. Undisturbed 
by the stream of impressions constantly pouring into the sensorium, they provide 
a mechanism for recording to an almost unlimited extent not only the mere 
visual, tactile, and other qualities of objects, and the states of consciousness 
each. awakens, but also the recollection of acts and their consequences, so that 
Man is endowed with such a wealth of experience of the consequences of certain 
lines of action that he is able to foresee the results of his behaviour and modify 
it accordingly. 
1912. QQ | 
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