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PROFESSORS D. FERRIER AMD G. F YEO ON THE EFFECTS OF 
General Results. 
These two experiments show that the auditory centre is situated in the superior 
temporo-sphenoidal convolution. For whereas hearing was totally abolished by des¬ 
tructive lesion confined to this convolution in both hemispheres, there was no im¬ 
pairment of hearing when the medullary fibres of the other convolutions of the tem¬ 
poro-sphenoidal lobe were broken up. 
SECTION III. 
Lesions of the Convolutions bounding the fissure of Rolando (Rolandic Zone). 
Experiment 15* (Plate 23, fig. 39). 
In this animal the skull was trephined over the region of the middle of the ascend¬ 
ing parietal convolution of the right hemisphere. The application of faradic elec¬ 
trical stimulation to this part of the cortex excited movements of the left hand and 
arm. The part to which the electrodes had been applied was then cauterised with the 
galvanic cautery. 
Three quarters of an hour after the operation the animal in attempting to walk or 
run fell over on the left side from obvious weakness of the left arm. This tendency 
to fall over on the left was frequently observed. An hour and a half after the opera¬ 
tion it was able to run on three legs, the left arm not being used. 
Next day the animal when resting kept the left hand hanging by the side. It 
took hold of things offered it only with the right hand. In walking it was able 
to advance the left arm, but limped, as if unable to bear weight on the hand. In 
climbing it used both legs and the right hand only. Beyond the loss of power in the 
left hand there was no other defect. The sensibility of the left hand was unimpaired, 
as the animal’s attention was excited by a touch on it, and a slight pinch caused it to 
exhibit uneasiness and desire to get away. 
On the fourth day the condition was the same. The animal advanced the left arm 
like the other limbs in walking, but seemed unable to bear weight on the hand, and did 
not use the left hand in climbing. Sensibility to heat on both hands was evidently 
equally acute. 
A fortnight after the operation the animal continued in all other respects well and 
strong, but limped with the left hand. A large piece of pear being offered to it, it 
laid hold of it only with the right hand, but finding it too large to hold conveniently 
in one hand, it did not use the left also, as other Monkeys would, but kept it steady 
while eating by making a point d’appui of the floor. It was observed some time 
after endeavouring to get a piece of bread out of the cage between the bars. As 
the piece was rather large and not easily extracted, the animal managed to put its left 
hand also through the bars, but was unable to grip the object. 
