492 
PROFESSORS D. FERRIER AND G. F. YEO ON THE EFFECTS OF 
impairment of vision could be detected, and it was able to pick up the minutest 
objects lying about in its cage or thrown down near it. 
The animal was a very agile jumper, and would take a flying leap over one’s 
shoulder when an attempt was made to lay hold of it. 
Five weeks after the above operation the right angular gyrus was exposed and 
similarly cauterised. 
During the dressing of the wound the animal had recovered from its stupor. The eyes 
were both open, the pupils small, and the conjunctival reaction distinct on both sides. 
When freed the animal almost immediately began to run about, knocking its head 
against various .obstacles. This, however, continued only for a few minutes, and 
within half an hour it was able to stoop under the cross bar of a table which came in 
its way, and on coming to its cage thrust its hand between the bars. At this time 
both eyes were left open. The right eye was now securely closed. Vision still 
continued, however, with the left eye to some extent, but indistinct, as it tried 
to lay hold of things before they were within reach. 
For an hour numerous and careful observations were made as to whether vision was 
impaired to one side more than the other, but this was clearly not the case, for the 
animal very speedily showed that it could see to both sides by picking up currants 
scattered on the floor to either side and w 7 ith either hand indifferently. 
The recovery was most rapid, and an hour after the operation it was not possible 
to detect any deficiency in the animal’s powers of vision, or otherwise. 
It continued in every respect perfectly well until its death by chloroform four 
months after the last operation. 
Post-mortem examination .—The surface of the brain w r as everywhere normal except 
in the region of the angular gyri, where the membrane, continuous with the dura mater 
stretching across the orifices in the skull, was adherent. On removal of this it was 
seen that the left angular gyrus was obliterated, its place being indicated by a depres¬ 
sion caused by the destruction of the cortex. At the bottom of the sulci separating 
the limbs of the angular gyrus from the ascending parietal convolution, the superior 
temporo-sphenoidal convolution, and occipital lobe, the grey matter was, however, 
uninjured. The lesion shelved gradually into the anterior boundary of the occipital 
lobe (fig. II). 
On the right hemisphere the lesion of the angular gyrus was less complete 
and more superficial. A thin strip of uninjured cortex bounded the intra-parietal 
sulcus, and the upper extremity of the arch formed by the two limbs of the gyrus 
was also visible. The convex aspeet of the limbs of the angular gyrus had been 
removed, but the folding of the grey matter in the bounding sulci was still very 
apparent and uninjured. The convex aspeet of the upper extremity of the superior 
temporo-sphenoidal convolution was also involved in the lesion, a considerable portion 
of this having been also destroyed. The lesion sloped gradually into the anterior 
boundary of the occipital lobe (fig. 10), 
