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PROFESSORS D. FERRIER AND G. F. YEO ON THE EFFECTS OF 
revealed the same absence of flinching or other sign of perception when a light was 
flashed in its eyes, and the same fixity of the pupils as before noted. 
Post-mortem examination .—The aspect of the brain was everywhere normal except 
in the occipito-angular region of both sides over which the membrane, continuous with 
the dura mater, was adherent. On removal of this it was seen that on the leftside, the 
occipital lobe had been severed and removed in a line corresponding with the internal 
parieto-occipital fissure, and the angular gyrus was obliterated both on its convexity 
and in the sulci, so that the neighbouring convolutions, the ascending parietal with the 
postero-parietal lobule, and the upper extremity of the superior temporo-sphenoidal, 
appeared as if dissected out and laid bare (fig. 22). 
On the right side the lesion was exactly symmetrical with that of the left, the 
occipital lobe being removed, and the angular gyrus entirely obliterated (fig. 21). 
The corpora quadrigemina and optic tracts looked smaller than usual, but beyond 
this had no abnormal appearance. The abdominal and thoracic viscera were healthy, 
but there was some emaciation and absence of fat in the omentum. No local disease 
could be discovered accounting for death. 
Remarks .—This case shows that the complete removal of the occipital lobes and 
angular gyri on both sides causes complete and permanent loss of vision, followed by 
atrophy of the optic discs and fixity of the pupils. Apart from blindness there was 
no defect either as regards motor powers or other faculties of sense. The whole aspect 
and behaviour of the animal resembled that of one blind, the loss of one sense being 
compensated for by the acuteness and education of the others. 
General Results. 
These experiments show that lesions of the occipito-angular region cause affections 
of vision, without affection of the other sensory faculties or motor powers. 
The only lesion which causes complete and permanent blindness is total destruction 
of the occipital lobes and angular gyri on both sides. 
If the lesion extend in front of this region into the ascending parietal convolution 
some affection of motion is seen in the upper extremity on the side opposite the lesion. 
Complete destruction of the angular gyri on both sides causes for a time total 
blindness, succeeded by lasting visual impairment in both eyes. 
Destruction of the convex aspect of the angular gyrus on one side causes temporary 
abolition or impairment of vision in the opposite eye. The defect is not of a hemiopic 
character. Subsequent similar lesion of the other angular gyrus causes bilateral visual 
defect, also only of transient duration. The rapidity of restoration of vision does not 
depend on the integrity of the corpus callosum. 
Deep incisions may be made in both occipital lobes, or the greater portion of one, or 
both occipital lobes at the same time, may be removed without causing any appre¬ 
ciable defect of vision. 
After removal of the greater portion of both occipital lobes lesion of one angular 
