LESION OF DIFFERENT REGIONS OF THE CEREBRAL HEMISPHERES. 529 
Except for general dulness and want of interest in its surroundings, the animal 
exhibited no perceptible effect of the operation, and continued in excellent health. 
Seven weeks after the operation chloroform was again administered, and the mem¬ 
brane covering the orifices in the frontal regions incised and the fronto-orbital margins 
of the hemispheres scooped out so as clearly to expose the roof of the orbits—the 
middle line and region of the olfactory bulbs being avoided. 
On the animal regaining consciousness, which it did very speedily, the head was 
observed to be in a state of rapid lateral oscillation, as rapid as the tremor of paralysis 
agitans. Within half an hour after the operation, while the lateral oscillation was 
continuing, the animal was able to climb up the bars of the cage hand-over-hand, 
holding the head well back and the trunk stiff. The right eyelid was observed to 
droop considerably. 
Tactile sensibility was unimpaired generally. 
An hour after the operation the tremor of the head was almost gone, and the 
animal occasionally made circus movements, pivoting itself on the buttocks, and 
turning round with the head en masse with the trunk. 
But within two hours some indications were seen of lateral movements of the head 
alone, apart from the trunk. 
Next day the animal was as usual dull, but opened its eyes if touched anywhere or 
called to. The right eyelid still drooped perceptibly. It moved its head freely back¬ 
wards and forwards, and also apparently to both sides. It was seen to shake its head 
vigorously from side to side, as if to remove itching. Sight was perfect, as also 
hearing, tactile sensibility, and to all appearance also smell, as it at once grabbed at 
a piece of apiple held under its nostrils. 
On the following day free movement of the head and eyes in every direction was 
clearly manifested, and from this time onwards it was impossible to discover any 
appreciable effect of the operation. The animal was killed with chloroform two 
months and a half after the first operation. 
Post-mortem examination .—Except over the prefrontal regions the membranes 
stripped readily without any sign of inflammation. 
On removal of the brain it was found that the olfactory tracts and bulbs were 
uninjured. 
The only lesion was in the frontal lobes (fig. 74). 
On the left side the cortex at the base of the superior and middle frontal convolu¬ 
tions was irregularly eroded, while the base of the third frontal was intact. The 
mesial surface of the superior frontal was also intact as far as the anterior extremity, 
a minute portion of which overlying the olfactory bulb was also uninjured. But the 
anterior two-thirds of the middle and inferior frontal convolutions and the orbito- 
frontal margin of the hemisphere had been destroyed. 
On the right side the superior frontal convolution was intact, as well as the mesial 
MDCCCLXXXIV. 3 Y 
