484 
PROFESSORS D. FERRIER AND G. F. YEO ON THE EFFECTS OF 
On the next day the left eye was bandaged, but there was no sign of impairment 
of vision in the right eye. 
The animal died eighteen days after the operation, the weather being intensely cold, 
and the temperature of the laboratory having sunk very low, from defect in the heating 
arrangements at the time. 
Post-mortem examination .—The scalp wound was healed, and there were no signs 
of hernia cerebri or inflammation. 
The brain was injured by the saw during removal, as seen in the photograph 
(Plate 20, fig. 4). 
The brain was everywhere normal except in the region of the right angular gyrus. 
This, as seen in the photograph, had the cortical substance eroded and disorganised 
over the convex aspect of both limbs. The depth of the lesion was comparatively 
slight, and the grey matter of the sulci separating the angular gyrus from the adjoining 
convolutions was not injured. A thin strip of uninjured cortical substance formed the 
posterior boundary of the intraparietal sulcus. 
Remarks .—In this case of unilateral lesion, not amounting to entire destruction of 
the angular gyrus, there was a temporary impairment of vision, after the animal had 
otherwise entirely recovered its other faculties and powers. 
At first, when both eyes were open, the defect was shown in inability to realise the 
exact position of objects. But when the right eye was closed, it was seen that vision 
was specially defective, if not for a time entirely abolished, on the side opposite the 
lesion. 
Next day no defect could be ascertained, either amblyopic or hemiopic, and the 
animal was in all respects apparently perfectly normal. 
Experiment 4* (Plate 20, figs. 5 and 6). 
In this animal the left angular gyrus was exposed and cauterised on the convexity 
so as to destroy the grey matter of the two limbs of this convolution. By the time 
the dressings were applied the animal was awake, keeping both eyes open, and looking 
about. The left eye was then securely closed, and the animal left to itself. After a 
few minutes it got up and began to sprawl about in its cage, knocking its head in 
every direction. 
Being; let out it walked straight on and came full tilt with its snout against the 
door. Then it turned away and walked in various directions, each time being brought 
to a standstill by knocking its head full against some obstacle. This condition of total 
blindness continued only half an hour. After this it began to give evidence of 
returning vision, at first imperfect, shown by attempting to seize and climb on to a 
hot pipe before it could reach it. But within two hours vision was acute enough to 
enable it to pick up a piece of apple lying to its right side ; and it was able to run 
about the laboratory with a companion, avoiding obstacles on either side, passing them 
quite closely and never running against them. There was no sign of hemiopia. 
