722m 
great centre of sensation, whether for mental or 
physical actions. 
he pyramidal bodies evidently connect the 
grey matter of the cord (its anterior horns ?) 
with the corpora striata; and not only these, 
but also the intervening masses of vesicular 
matter, such as the locus niger, and the vesi- 
cular matter of the pons, and of the olivary 
columns; and, supposing the corpora striata 
to be centres of volition in intimate connection 
with the convoluted surface of the brain by 
their numerous radiations, all these several 
parts are linked together for the common pur- 
poses of volition, and constitute a great centre 
of voluntary actions, amenable to the influence 
of the will at every point. 
It has been pretty generally admitted by 
anatomists, that both the corpora striata a 
the anterior pyramids are concerned in volun- 
tary movements. The motor tracts of Bell 
were rded by that physiologist as passin 
pirate I from the sated ie columns of the cord 
to the corpora striata, and, after traversing 
those bodies, as diverging into the fibrous mat- 
ter of the hemispheres; and the fact of the 
origin of certain motor nerves, in connection 
with those fibres, was considered to be very 
favourable to this view. The decussation of 
the pyramids, likewise, so illustrative of the 
cross influence of the brain in lesions sufficient 
to produce paralysis, has been looked upon as 
an additional indication of the motor influence 
of these parts. 
The invariable occurrence of paralysis as the 
result of lesion, even of slight amount, in the 
corpora striata, must be regarded as a fact of 
strong import in reference to the motor func- 
tions of these bodies. 
Nor is this fact at all incompatible with the 
statements made by all experimenters, that 
simple section of the corpus striatum does not 
occasion either marked paralysis or convulsion ; 
and that in cutting away the different segments 
of the brain, beginning with the hemispheres, 
convulsions are not excited until the region of 
the mesocephale is involved. The influence of 
the corpora striata is not upon the nerves di- 
rectly, but upon the segments of the medulla 
oblongata or of the spinal cord, and, through 
them, upon the nerves which arise from them. 
Were the nerve-fibres continued up into the 
corpora striata, according to an opinion which 
has been long prevalent, there would be no 
ood reason for supposing that they should 
‘ose in the brain that excitability to physical 
stimuli which they are known to possess in the 
spinal cord, and at their peripheral distribution. 
The latest experiments of this kind, which are 
those of Longet and Lafargue, agree in the fol- 
lowing result, which is not at variance with that 
obtained by Flourens. The animals remain 
immoveable after the removal of the corpora 
striata, whether those bodies have been removed 
alone or in conjunction with the hemispheres ; 
nor do they show any disposition to move, un- 
less strongly excited by some external stimu- 
lus. None of these observers had noticed the 
irresistible tendency to rapid propulsion, which 
was described by Magendie. Removal of the 
PHYSIOLOGY OF THE NERVOUS SYSTEM. 
corpus striatum of one side caused weakness 
of the opposite side. 
ln order to form a due estimate of these ex- 
periments, it must be borne in mind, that the 
effects of simple excision of either corpus 
striatum would be very different from those of 
disease of it. The depressing effects of the 
latter would be absent, at least, until some 
alteration in the process of nutrition had been 
set up in the mutilated Simple excision 
of the centre of volition, and inflammatory dis- 
ease of its substance, or an tot sonar 
must produce essentially different effects ;- 
the one simply cuts off the influence of the 
will, the other affects the vital action, and, com= 
sequently, the vital of the centre, and 
of the commissural fibres connected with it. 
Judging from structure only, it might be 
conjectured that the locus niger, that remark- 
able mass of vesicular matter bree $s 
the anterior and posterior planes us 
cerebri, estore & davtob atapeiin Tt resemb ‘ 
in structure the anterior horns of the @ rey 
matter of the cord, and contains numérous 
large caudate vesicles with very abundant pig- 
ment, and is the immediate centre of implanta 
tion of a very im t motor nerve, the thi 
pair, which regulates the movements of 
all the muscles of the eyeball. 
Optic thalami—The same line of arg 
which leads us to view the striate 
the more essential of the nervous 
ratus which controul direct voluntary mo 
ments, suggests that the optie thalami may | 
viewed as the principal foci of. sen 
without which the mind could not pere 
physical change resulting from a se 
pression. ae 
The principal anatomical facet which fa 
this conclusion is the connection of a 
nerves of pure sense, more or less di 
with the optic thalami or with the olivary 
lumns. e olfactory processes, which a 
rently have no connection with them, fe 
doubt, t h the fornix, such an union Wi 
them, as readily to bring them within the 
fluence of the olfactory nerves. “ 
According to this sense of its office we 
regard the optic thalami as the upper and 
fd of an sane 
wer part is formed olivary ec 
which oa have ie referred to as ti 
part in the mechanism of sensation. The 
tinuity of the olivary columns with the” 
thalami justifies this view: nor is it it 
by the fact, that some of the nerves 4 
arise from the medulla oblongata are mo 
function; for Stilling’s researches re 
probable that these fibres have their ori 
special accumulations of vesicular matter, ¥ 
contain caudate vesicles of the same 4 
those found in the anterior horns of the 
matter of the cord. ( 
The results which experiments have yie 
add little that is positive to our knowled 
the functions of these bodies. Flourens 
that neither pricking nor cutting away the oj 
thalami by successive slices occasioned 
muscular agitation, nor did it even mduce’ 
is 
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