LESION OF DIFFERENT REGIONS OF THE CEREBRAL HEMISPHERES. 511 
A few days subsequently it was seen climbing up the bars of the cage in a peculiar 
manner. It did not climb hand over hand like Monkeys generally, but proceeded 
staccado fashion, clinging with the feet, and springing and laying hold higher up with 
the right hand only. 
A month subsequent to the operation the condition was essentially the same. It was 
observed on one occasion after it had climbed in its peculiar manner to the top of the 
cage, to put out the left hand for support, but venturing to lean its weight on it, it 
fell to the ground. 
Seven weeks after the operation the animal was taken out and held while the 
relative strength of the hands was tested. The grip of the right hand was strong 
and vigorous when ones fingers were placed in it, but on the left side there was 
scarcely any perceptible pressure. The slightest pinch caused desire on the part of 
the animal to have the hand released, but the power exerted was very feeble, both as 
regards the hand and flexion of the forearm. 
The animal was found dead one morning two months after the operation, evidently 
from the effects of cold. The season was the middle of winter and the cold intense. 
The heating arrangements of the hutches had also failed to keep the temperature up 
to the usual standard. 
Post-mortem examination. —The brain was everywhere normal, except in the region 
of the middle of the ascending parietal convolution in the right hemisphere. Here 
the cortex was destroyed, and the medullary fibres exposed, over a somewhat irregular 
area about the size of a threepenny bit. The erosion trenched anteriorly on the 
fissure of Rolando, while posteriorly there was an elongated superficial erosion of the 
cortex of the anterior limb of the angular gyrus. 
The upper margin of the lesion was abrupt (fig. 39). 
Remarks. —The effect of this limited lesion of the middle third of the ascending 
parietal, and adjoining margin of the ascending frontal convolution, was weakness, 
not amounting to absolute paralysis, of the left hand, and to a less extent of the 
power of flexion of the forearm. The sensibility was unimpaired. There was no 
other defect. Though there was some erosion of the anterior limb of the angular 
gyrus also, this had nothing to do with the motor defect, as is sufficiently plain from 
the experiments related in Section 1, where it has been shown that no motor paralysis 
occurs from complete destimction of this gyrus. Some experiments were also related 
in this section, showing that weakness of the opposite hand occurred when the lesions 
extended across the intraparietal sulcus into the ascending parietal convolution. 
Experiment 16* (Plate 23, figs. 40-44). 
In this case the left hemisphere was trephined over the upper ext remit p of the 
fissure of Rolando, and the cortex destroyed at this point with the galvanic cautery. 
An hour after the operation the animal was able to walk, but in a lame manner, 
dragging the right leg. 
