LESION OF DIFFERENT REGIONS OF THE CEREBRAL HEMISPHERES. 497 
Next day similar tests were employed with precisely similar results. The left eye 
which had been closed, was freed to-day, but no difference was observable in the 
animal’s behaviour or power to pick up things. 
From this time onwards the animal seemed in every respect perfectly well. It was 
very active and vivacious, and constituted itself leader and protector of its companions. 
It was killed with chloroform nine months after the first operation. 
Post-mortem examination ,—The brain was everywhere normal except in the follow¬ 
ing particulars :— 
In the left hemisphere the convex aspect of the limbs of the angular gyrus was 
superficially eroded, with the exception of a strip of uninjured cortex bounding the 
intraparietal sulcus. The grey matter in the sulci was uninjured (Plate 21, fig. 15). 
The left occipital lobe was represented only by a small angular portion behind the 
upper extremity of the parieto-occipital fissure. 
In the right hemisphere the angular gyrus was intact, but the occipital lobe was 
represented only by a truncated portion, scarcely one-third of the whole, of a triangular 
shape, the base directed upwards and the apex downwards, the boundary of the section 
being at the vertex half an inch behind the parieto-occipital fissure, and thence 
gradually tapering to one-sixteenth of an inch behind the lower extremity of this 
sulcus. 
Remarks .—This case shows very clearly that notwithstanding the entire removal of 
at least two-thirds of both occipital lobes, the animal, within two hours of the opera¬ 
tion, was able to see and pick up minute objects with perfect precision, recognised and 
interpreted the meaning of threatening gestures, and acted generally as if it retained 
its visual faculties in all their integrity. 
The additional superficial lesion of the left angular gyrus induced transient total 
blindness in the right eye, gradually giving place to such restoration of vision that 
next day it was impossible to detect any visual defect either to the one side or the 
other. 
Though therefore the left occipital lobe was almost entirely removed, and the left 
angular gyrus extensively injured, and two-thirds of the right occipital lobe destroyed, 
the animal enjoyed vision so perfect that no defect could be discovered by any tests 
applicable to lower animals, continued most intelligent and vivacious, and exercised a 
dominant influence over its companions. 
Experiment l'“ showed that almost entire removal of one occipital lobe was without 
appreciable effect on vision ; and Experiment 2* showed that considerable bilateral 
lesions were also negative. This experiment is still more striking, 
Reference is also made to “ Experiments on the Brain of Monkeys ” in the Philo¬ 
sophical Transactions, Yol. 165, Part 2, by Dr. Ferrier. In Experiments XXII. and 
XXIII. similar facts are related. In Experiment XXIV., in which the occipital lobes 
(and subsequently also the greater portion of the frontal lobes) had been removed, there 
was some defect in vision, shown in incorrect appreciation of the distance of objects. In 
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