LESION OF DIFFERENT REGIONS OF THE CEREBRAL HEMISPHERES. 513 
The animal, otherwise perfectly well, was killed with chloroform at the end of this 
period—eight months after the operation. 
Post-mortem examination .—The brain was everywhere normal except in the region 
of the upper extremity of the fissure of Rolando in the left hemisphere. Here the 
membrane which covered the orifice in the skull was adherent. On this being sepa¬ 
rated, a destructive lesion of the cortex was found, consisting of a cavity or hollow 
depression caused by loss of substance, situated at the upper extremity of the 
ascending parietal and frontal convolutions, running across the upper end of the 
fissure of Rolando, parallel to the longitudinal fissure. The cavity commenced 
1 centim. anterior to the parieto-occipital fissure, and extended forwards for 1'5 centim. 
Anteriorly it tapered and passed into a superficial erosion, caused by adhesion and 
separation of the dura mater there, which occupied an irregular area over the upper 
extremity of the ascending frontal, and base of the first frontal, convolutions. 
These appearances are seen in the accompanying photograph, which is somewhat 
larger than the natural brain (fig. 40). 
Frontal sections through the lesion showed that it was purely superficial, the cortex 
being merely sheared away from the subjacent medullary fibres. 
The medullary fibres proceeding from this point to the internal capsule were the seat 
of degeneration, and stained less readily with carmine than the rest of the medullary 
fibres. This is seen in the accompanying sun-print of one of these sections (fig. 41). 
Microscopical investigation of the spinal cord after hardening in bichromate of 
ammonia, demonstrated the existence of an area of sclerosis in the pyramidal or 
postero-lateral tract of the right side of the spinal cord through the cervical, dorsal, 
and down to the lumbar region. 
Figs. 42-44 are microphotographs, enlargements of about 12 diameters, of a section 
of the cervical (fig. 42), dorsal (fig. 43), and lumbar region (fig. 44) of the cord respec¬ 
tively. The sections were somewhat imperfect owing to the cord being rather brittle 
from too long maceration in the bichromate solution, but they show very clearly 
the dark area of sclerosis external to the posterior horn in the cervical region ; 
the same in the dorsal region approaching nearer the surface, and somewhat less 
distinctly, owing to less perfect section and photograph, immediately external to the 
posterior horn of the lumbar region, coming quite superficial at this point. [Figs. 43 
and 44 have been printed too dark.] 
Remarls .—This case shows very clearly that a lesion of the cortex in the region 
where electrical irritation causes movements of the opposite leg, gives rise to a 
permanent monoplegia of this limb ; the affection being one purely of motor power 
without loss of sensation. The lesion did not involve the whole of the cortical region, 
irritation of which causes movements of the opposite leg, nor was the paralysis of the 
leg absolute, nor did it affect all movements equally. Those most affected were the 
movements of the foot. The case further demonstrates the important fact that a 
purely cortical lesion is followed by descending degeneration through the whole 
MDCCCLXXXIV. 3 IT 
