722k 
the medulla on either side would affect the 
same side of the body, no decussation existing 
between the fibres of opposite restiform or pos- 
terior pyramidal bodies. The irritating or de- 
es influence of the lesion would probably 
extended to the spinal grey matter of the 
same side. 
That the medulla oblongata is the channel 
through which the operations of the brain are 
associated in voluntary actions with the spinal 
cord, is shewn by the fact that paralysis of all 
the muscles of the trunk follows the separation 
of the latter organ from the former. It seems 
not improbable that the centre of volition is 
connected with one of the gangliform bodies 
in which the columns of the medulla oblon- 
gata terminate above (the corpora striata), so 
that the column connected with each corpus 
striatum (the anterior pyramid) is well placed 
for conveying voluntary impulses downwards. 
When the cerebral hemispheres have been 
removed, as in Flourens’ and in Magendie’s 
experiments, the bird is thrown into a deep 
sleep, a state of stupefaction, and insensibility 
to surrounding objects. But as he can main- 
tain his attitude, stand, walk when first pro- 
lled, fly if thrown into the air, it may be 
inferred that some degree at least of mental 
or volitional effort remains. Some of the ani- 
mal’s movements have the appearance of the 
exercise of will, although, doubtless, many of 
them are’in a great degree excited by physical 
stimuli. I may instance, in particular, what I 
have noticed in my own repetition of Flourens’ 
experiments, a peculiar movement of the head, 
as if the bird were trying to shake off some 
object which irritated the head, and a frequent 
opening and shutting the bill, with movements 
of deglutition. Hence there seems reason to 
believe that the will may be exercised inde- 
pendently of the cerebral convolutions and 
their fibres, and that, under all circumstances, 
it exerts a primary influence upon either or 
both of these gangliform bodies, more vigorous 
when aided and guided by the power of the 
cerebral hemispheres. The frequent paralysis 
of motion apart from sensation, when the up- 
ward continuations of the pyramidal fibres in 
the corpora striata are diseased, renders it ex- 
tremely probable that these fibres are the media 
of connection between the brain and cord in 
voluntary actions. 
The medulla oblongata is also the medium for 
the transmission of sensitive impressions from 
all the regions of the head, trunk, and extremi- 
ties; and from its olivary columns at their upper 
and posterior part in the mesocephale being, as 
it were, the concourse of all the nerves of pure 
sense, it seems fair to assign these parts as the 
prime seat of those central impressions which 
are necessary for sensation. e reception of 
these impressions by the cerebral hemispheres 
is the stage immediately associated with mental 
perception. Perfect sensation, therefore, cannot 
take place without cerebral hemispheres. Ina 
sensation excited in parts suppled by spinal 
nerves, the first central change is probably in 
the posterior horn of the vesicular matter of the 
PHYSIOLOGY OF THE NERVOUS SYSTEM. 
cord; and the olivary column of the medulla — 
oblongata is simultaneously affected, from its 
connection with the cord. The change in this 
latter part is then propagated to the cerebral 
hemispheres. 
Thus much is suggested by anatomy, as re=— 
gards the share which the medulla oblongata — 
takes in the mechanism of sensitive impressions, 
Experiment affords us no aid in this intricate — 
and difficult subject; neither does peholeaay 
anatomy : for the parts are so closely associated 
with each other, that any morbid state of one 
readily involves the others, so that it is almost 
impossible to find a morbid state of the p 
devoted to sensation, apart from an affection: 
those more immediately concerned in motion, 
The function of the restiform bodies is pro- 
bably associated with that of the hemisp 
of the cerebellum, and of the posterior columns — 
of the spinal cord. ae 
The experiments of Le Gallois and Flourens — 
make it certain that the medulla obl is 
the centre of respiratory movements. : 
ter physiologist assigns as the “ primum 
vens”’ of these acts all that portion of the me- 
dulla which extends from the filaments of ori 
of the vagus nerve to the tubercula quadrig 
mina, the former only inclusive. Dest 
of this portion, in whole or in part, invariabl 
impairs or destroys the respiratory actions, ant 
a morbid state of it gives rise to irregular © 
excited movements of respiration. Sighing 
yawning, coughing, are probably connected 
excitation of this centre, either direct, or f 
gated to it from some sentient surface 
seems not improbable that a portion of 
spinal cord as low down as the spinal 
sory nerve goes, is associated with this ce 
in the respiratory movements. th 
This portion of the encephalon is 
centre of action in the movements of de 
tion, through fibres of the glosso-pharyngs 
and vagi nerves. A morbid state of it occasio 
difficulty, or even bayer of deglutitio 
Animals deprived of the cerebral hemisp 
and cerebellum will preserve the pe 
swallowing food introduced within tl 
of the fauces, so long as the medulla oblon 
continues uninjured. In foetuses born 
cerebral hemispheres, those actions are p 
which depend on the spinal cord and me 
oblongata; all the movements of respirat 
and deglutition are performed as well as in 
perfect fetus. Mr. Grainger’s experim 
shew that puppies deprived of the hemisph 
of the brain can perform the movemen 
suction with considerable vigour, » 
finger is introduced into the mouth ;* ane 
remarkable fact of the adhesion of the fa 
the kangaroo to the nipple within the pot 
no less than its respiratory movements, mus 
this author remarks, be regarded as a most 
teresting display of the physical power oi 
medulla oblongata, while the rest of the bra 
as yet undeveloped. a 
The actions of respiration and phary 
we, 
ie 
. 
* Loc, cit. pp. 80-1, 
