ON THE FUNCTIONS OF THE CEREBRAL CORTEX. 
.17 
of opinion that it is the superficial layers of smaller cells of the grey cortex that are 
immediately connected with the sensory tracts, and the larger cells of the deeper 
layers of the cortex that give origin to the fibres of the motor tract. 
In order to test this last opinion, we in one instance endeavoured to destroy, 
by searing the surface of the excitable region of the brain with the actual cautery, the 
superficial part of the grey matter, while leaving the deeper layers of nerve-cells 
intact. In spite of the complete blocking of the superficial vessels which is produced 
by this treatment, we obtained only an incomplete muscular paralysis as the 
immediate result of the operation ; but, although the superficial layers of the cortex 
must have been destroyed, there was no diminution of sensibility in the parts affected 
by paresis. The subsequent softening and disintegration which occurred in 
consequence of the thromboses caused by the cautery was accompanied by a much 
more complete condition of muscular paralysis ; but the general sensibility of the 
opposite side was still apparently unaffected, and continued so until the death of the 
animal (see ' Eecord of Experiments,' Case 6, and fig. 6, Plate 1). 
The result of this experiment, so far as it goes, is opposed to the opinion in question, 
but we would disclaim attaching too much importance to a single case of the kind, 
especially since the depth of the primary lesion could not have been uniform, and was 
probably much less in some parts than in others. It must be admitted that the 
question whether there is any localisation of sensibility, either for the muscles which 
are governed from the cortical motor regions or for the parts which they move, is one 
which can scarcely be answered by experiments upon animals, and that for its solution 
we must await the result of clinical and pathological observation upon Man.'"" 
* H. MuNK (' Ueber die Fuuctioncii der Grosshirnrindc, 4tc Mittlieilniig,' tig. 4, p. C8) has 
mapped out the external surface of the Monkey's brain in a manner which, in certain particulars, 
corresponds with the plan we have here given (in Diagram I.). Although he regards the areas in 
question as sensory rather than motor, the difference is merely one of terms, for the facts upon which he 
rests this opinion are nearly the same as those which have guided us in arriving at our results. For the 
author (p. 66) admits that he has found it difficult to prove that after extirpation of his so-called 
" sensory areas " in Monkeys there is any loss of sensibility, at least to pressure, and it seems to be a 
mere assumption that other forms of sensation, such as tactile sensibility and the muscular sense, are 
abolished. Dismissing, then, the question of nomenclature, the two plans, so far as they deal with the 
same regions, are strictly comparable. 
On instituting such comparison, we find that our leg-, arm- and face-areas very nearly correspond with 
those of MuNK (who, however, designates as head-region that which we term the face- area, but connects 
it with the movements of the same parts as onv face-area is concerned with). The main differences are 
to be found in the other tvro areas, viz., those for the trunk and head and eye movements respectively. 
Monk's trunk-region occupies the prefrontal lobe, whilst ov,v trimlc-areai?, comprised within the leg-region 
of MuNK. "We have already given our reasons for believing that Munk is altogether mistaken in 
believing that the prefrontal region is concerned with movements of the trunk. The area concerned 
with rotation and lateral movements of the head, which MuNK designates the neck-region, ajjpears far 
smaller than the corresponding area in our plan, and even much smaller than that given by Fkruier. 
MDCCCLXXXVIIJ. — B. 
