ON THE FUNCTIONS OF THE CEREBRAL CORTEX. 
27 
8.''- 
Lesions. — In this animal a lesion liad been established in the posterior part of the 
gyrus fornicatus on the right side, but the Monkey was at first so wild that no definite 
result could be obtained regarding loss of sensibility. It was therefore determined 
to employ it for an operation upon the motor region, and accordingly sixteen days 
after the first operation a lesion was effected in this part. The lesion consisted in the 
removal of the greater part of the motor area of the external surface on the 
right side. 
Result. — The result of this second lesion was to cause paralysis of the left arm and 
paresis of the leg, with the exception of the extensor muscles of the thigh, which 
acted normally. 
Experiments upon the sensibility of the left side were again tried, but again 
.with very unsatisfactory results. Sometimes there was no movement caused by 
a stimulus applied to that side, when there would be marked movement produced 
on applying the same stimulus to the right side, but, on the other hand, this may well 
have been the result of the establishment of the motor paralysis, for on stimulation 
of the left side the animal, without moving away, would occasionally exhibit 
dissatisfaction by squeaking. 
The paralysed condition was maintained until the animal was killed three-and-a-half 
months after the second operation. 
The brain is represented in fig. 8, Plate 1. 
9. 
Lesion. — Excision of the middle two-thirds of the left ascending parietal gyrus, 
including a small portion of the parietal lobule. 
Result. — The only result produced by this lesion was paresis of the fingers of the 
opposite hand, power of both flexion and extension being diminished. 
The animal was kept two months after the operation. 
The brain is represented in fig. 9, Plate 1. 
- 10. 
Lesion. — Complete removal of posterior two-thirds of right marginal gyrus. 
Result. — Left foot paralysed ; the toes opposed, semi-flexed, and with hallux turned 
under them. Hamstrings are almost completely paralysed ; also glutaei, extension of 
hip being very feeble. In standing and leaping, the right leg is almost exclusively 
used ; when lowered towards the ground, puts down right leg, never left. Can jiex 
left leg and even manage to scratch left side of trunk with it, but to scratch the 
left side of the neck the right hand is used. The tail tends to lie over on the right 
side. No other paresis observable. Can advance and flex left arm and grasp well 
with fingprs of left hand. Can turn head to left. 
* Exhibited to the Neurological Society. 
E 2 
