LESION OF DIFFERENT REGIONS OF THE CEREBRAL HEMISPHERES. 525 
nut seem to act with so much vigour as the left in its spontaneous movements. It 
was unable to sit up. 
Next day the animal was found in a sort of dozing condition, but opened its eyes 
when called to, or if touched anywhere. It was able to move all four limbs ener¬ 
getically and grip firmly with both hands and feet. It was also seen to move its head 
backwards and forwards. It could extend its trunk, but was unable to sit up. It 
could also move its tail, and its facial muscles were seen to act normally when the 
animal grinned, which it did if disturbed. 
The animal died suddenly when being fed. 
Post-mortem examination .—Examination showed that the cause of death was a 
recent hsemorrhage which filled the anterior fossa of the skull, and extended to some 
extent over the convexity of the hemispheres, and towmrds the base of the brain. 
Both frontal lobes had been completely removed by a frontal or transverse vertical 
incision immediately anterior to the precentral sulcus on each side. The base of the 
superior frontal convolution, and a small portion of the base of the middle frontal 
convolution at the upper bend of the precentral sulcus still remained intact however. 
The whole of the frontal lobes in advance of this had been divided down to the 
orbital surface, the incision being just anterior to the optic commissure, which, with 
the optic nerves, was uninjured. The olfactory tracts had also been severed, less 
completely on the left than the right. 
The temporo-sphenoidal lobes were intact. On the surface of the plane of section 
were clearly seen the divided anterior portion of the corpus callosum, and the head 
of the corpus striatum which was cut somewhat further back on the left side than 
on the right. 
Remarks .—Notwithstanding the formidable character of the operation, life might 
have continued but for fatal secondary haemorrhage. The amount of recovery 
within an hour of the operation w r as very remarkable. 
The animal retained consciousness, was able to make volitional movements with 
all four limbs, though owing to the greater amount of lesion in the left hemisphere, 
the right limbs were not so strong as the left. Vision was retained, as well as 
hearing and tactile sensibility. The facial movements were unimpaired. 
The only defect observed was the inability of the animal to move its head laterally 
or sit up, though it was able to extend the head and trunk. 
Experiment 22 (Plate 26, figs. 60-73). 
In this animal both frontal lobes were exposed towards their anterior extremities, 
the middle frontal sulcus being visible in the centre of the exposed region. The 
tip of the frontal lobes could be reached and raised with the handle of a scalpel. 
Electrical exploration was made of the exposed frontal lobe on the right side. 
Irritation at the base of the superior and middle frontal convolutions—centre 12 
(Ferrier) —caused movement of the head and eyes to the left. 
