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PROFESSORS D. FERRIER AND G. F. YEO ON THE EFFECTS OF 
On the fifteenth clay the reaction to thermal stimulation was still perceptibly less 
vigorous on the left than on the right, but three weeks after the operation no difference 
could be perceived, and the hemiopia formerly existing was no longer discoverable by 
any test. 
Four weeks subsequent to the operation on the right hemisphere the left occipital 
lobq was exposed and a wire cautery pushed through the occipital lobe at the anterior 
extremity of the first occipital sulcus, downwards and forwards approximately in the 
direction of the hippocampus. 
Half an hour after the operation the animal was able to move about spontaneously, 
but it tended to slip and fall over on the right side. The reaction to thermal stimula¬ 
tion at this time was most active on the left, but much less on the right, though it was 
not entirely absent. Next day more thorough examination of the animal revealed a 
condition of total blindness towards the right, and evidently, also, some impairment 
towards the left. 
Hearing was also impaired, if not abolished on the right, as the animal did not turn 
its head to scratching sounds, &c., made near its right ear, as it did to sounds made on 
the left. 
No definite conclusions could be arrived at as regards taste or smell, but these senses 
did not seem to be affected, as the animal smelt at its food in the usual way and 
seemed to enjoy it. 
Tactile sensibility was still markedly defective on the right side. The animal could 
not be touched anywhere on the left side without its attention being roused, and 
causing it to put its hand to the spot, but the right hand, foot, and right side of the 
tail could be touched without the animal seeming to be aware of the fact. Sometimes 
the difference seemed doubtful when the face was touched. 
The right foot frequently slipped off the perch, and sometimes the animal rested with 
the toes of its right foot doubled up on the plantar surface. 
The same condition as to the various senses was again determined by careful exami¬ 
nation on the twelfth day after the operation. 
On the fourteenth day blindness to the right side continued, but vision to the left was 
now good. 
No difference could now be made out between the acuteness of hearing on the right 
and left. 
Defective perception of mere contact was still evident on the right side, and 
apparently more so on the foot than elsewhere. 
A month after the operation the defective perception of tactile stimuli was still 
observable on the right foot, but less so than before. The animal still seemed 
absolutely blind towards the right. 
Two months after the operation the animal was still absolutely hemiopic to the 
right, but otherwise presented no abnormality. 
Ophthalmoscopic examination of the eyes four months after the operation did not 
