MOTOR CORTEX AND INTERNAL CAPSULE IN AN ORANG-OUTANG. 151 
in the psychical order of events, i.e. (1), direction of the head towards the danger ; (2) 
initial movement of flight. 
In the Orang the case is otherwise. The vertical posture requires much purposive 
action. An Orang placed under the same circumstances as the Bonnet rises on to its 
hind limbs by extension of the hip ; we, therefore, find that this movement is repre¬ 
sented in this animal to great excess compared to that of flexion. 
Further, in accordance with the now well recognised fact that as the foci of function 
are more spread over the convex surface of the hemisphere from the longitudinal 
towards the Sylvian fissure, so they are more highly, he., purposively evolved, it is 
clear that in the Orang the hip possesses a far higher character of representation than 
it has in the Bonnet, and we believe that this subserves the vertical posture. In 
addition, just as in the Bonnet the anatomical juxtaposition of the foci corresponds 
with the psychical order of events, in the Orang it is seen also that the focus of direc¬ 
tion of the head towards the source of danger is situated helow the focus for the hip— 
below because, as will be seen, what in the upper part of the hemisphere is horizontally 
directed in the Bonnet Monkey becomes vertically arranged in the Orang. 
III. Integration of Foci. 
The extraordinarily integrated character ot representation of individual movements 
in the several foci thus observed is of such extreme importance in elucidating the 
mode of localisation of function in the brains of the highest animals, the main object 
of the present research, that we shall now examine their arrangement in successive 
detail from this standpoint. 
The most important facts to notice in the comparison of the representation of the 
Anthropoids and Man with that in the Macacque and similar Monkeys, the highest 
animals on which experiments on the brain have hitherto been conducted, are that— 
1. Instead of the excitable area of the cortex being continuous, it is (in the Orang) 
much interrupted by spaces from which no effect could be obtained even by the 
application of strong stimuli. 
The inexcitable areas are indicated on fig. 3, and it will be noticed that they 
separate the areas of representations of the larger divisions of the body, and do not 
separate those for the segments of such divisions. 
2. Beference to the figures shows also that a large part of the cortex generally 
considered to be excitable was not so in the Orang. This is especially the case in the 
frontal lobe, the whole of which in front of the ascending frontal gyrus was inexcitable, 
with the exception of the area for the representation of turning the eyes to the 
opposite side, which is just in front of the priecentral sulcus. See figs. 1 and 3. 
Similarly, the ascending parietal gyrus gave relatively much fewer results than the 
same gyrus in the Bonnet Monkey, being practically wholly inexcitable in its upper 
third (the superior parietal lobule). 
