LESION OF DIFFERENT REGIONS OF THE CEREBRAL HEMISPHERES. 491 
The animal died two days after the operation, apparently from general prostration. 
Post-mortem examination .—On examination of the wound there was no sign of 
repair, the edges being ununited. The hemispheres were slightly glued together in 
the longitudinal fissure, evidently by haemorrhagic effusion, and this was particularly 
in the meshes of the pia mater along the inner aspect of the ascending frontal and 
parietal convolutions. The cortex here was somewhat softened, evidently caused by 
the operation. 
On separating the hemispheres it was seen that the corpus callosum had been 
completely divided, from within a quarter of an inch from the anterior extremity or 
genu, to the posterior extremity or splenium, where only a few transverse fibres over 
the corpora quadrigemina remained undivided. There was no effusion into the 
interior of the ventricles, and the brain, except at the region above mentioned, was 
otherwise perfectly normal. 
Remarks .—The weakness of the right arm and leg in this case is readily accounted 
for by the partial lesion of the cortex of the upper and inner aspects of the ascending 
convolutions. Otherwise the operation of division of the corpus callosum is seen to be 
entirely negative as regards sensory or motor powers. 
Experiment 1* (Plate 20, figs. 9, 10, 11). 
In this animal the left angular gyrus was exposed and cauterised up to the parieto¬ 
occipital fissure, and an aneurism needle was inserted between the hemispheres, and 
the corpus callosum torn through to a considerable extent. 
The left eye was securely closed, and the animal allowed to recover from its narcotic 
stupor. 
In half an hour it began to move about spontaneously, though rather unsteadily. 
An hour and a quarter after the operation it walked about the laboratory, knocking 
its head against legs of chairs and other obstacles in its path. 
When a piece of apple was held under its nose, it grabbed it and ate. It continued 
to walk about here and there, every now and then coming to a dead halt full tilt 
against a wall. 
Three hours after the operation it again, in running through the laboratory, came 
full tilt with its snout against a wall, where it rested. While it was resting quietly 
we crept up to it, but the animal, though with eyes wide open and looking towards us, 
made no sign of perception. Threatening grimaces likewise were without effect, but 
on making a noise with our lips the animal seemed alarmed, peered forwards, and yet, 
though it came quite close to our faces, seemed to see nothing. It was tried to right 
and left in the same way, but there was no sign of vision to one side or the other. 
Next day, the left eye being still closed, the animal ran about in every direction, 
ducking under bars, passing objects to right and left with the utmost precision, and 
never once knocking against anything on one side or the other. Not the slightest 
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