24 
PROFESSORS V. HORSLEY AND E. A. SCHAFER 
that the evidence of the exact locaHsation, in a particular region — and that a compara- 
tively limited one — of the cerebral cortex, of a function so universally distributed over the 
body as common sensation, affords the strongest corroboration of the evidence already 
-accumnlated on the question of cerebral localisation by the demonstration of the 
localisation of speech, of voluntary motions, and of certain special sense functions in 
particular parts — all of which has tended to show that, in the higher vertebrates at 
least, such localisation of cerebral function is carried out to a remarkable and, previously 
to the experiments of Fritsch and Hitzig, an entirely unsuspected extent. 
As for the view, originally put forth by Schiff and extended by H. Mcjnk, which 
has been already referred to (p. 16), we would merely now point out that, although 
this portion of our researches cannot be said to have directly disproved Munk's 
hypothesis, it must yet be admitted that it has rendered that idea unnecessary. For, 
as we have already endeavoured to show, the only evidence in favour of Munk's view 
is the slowness of reaction of a paresed part, and this slowness of reaction may be 
explained otherwise than by the assumption of a defect in sensibility. But if without 
any muscular paresis we can obtain by a definite and localised lesion complete tactile 
anaesthesia of a limb, while by a lesion in a different part of the cortex we can produce 
complete muscular paralysis without any perceptible anaesthesia, the conclusion that 
the part of the brain involved in the first lesion is alone concerned with the 
appreciation of sensibility in that limb, to the exclusion of the part involved in the 
second lesion, seems logically irresistible. 
Recoud of Cases. (See Plates 1-7."") 
1. 
Lesion. — Removal of the prefrontal part of the brain (anterior fourth of frontal 
Jobes) on both sides at one operation. 
This animal was kept alive five months, during which time no abnormal symptoms 
of any kind were noticeable. Careful testing showed no apparent deficiency of 
sensibility. The animal seemed lively and intelhgent throughout. 
The brain is represented, as seen from above, in fig. 1, Plate 1. 
2. 
Lesion. — Complete removal of prefrontal region on both sides by vertical incision. 
The lesion extended a little further back than in the preceding case. The orbital 
part was included in the removal, but the olfactory tracts were left. 
* With one or two exceptions, the post-mortem condition of the brain in each case is represented with 
the exact superficial extent of lesion marked out by darker shading. The numbers attached to 
the figures correspond with the numbers of the cases in the record. In some instances sections of the 
brain are also given to show the deep extent of the lesion. Most of the drawings were made for us by 
Mr. E. P. France, Assistant in the Physiological Laboratory, and we can answer for their fidelity. 
Mr. France has also executed casts of the brains : these casts we have deposited in the Museum of 
University College. 
