428 Progress of Foreign Science. 
oblongata, the tubercula quadrigemina, the cerebellum, and the 
cerebral lobes. From these experiments, thus chalked out, it 
follows :— 
1st. That the nerves, the spinal marrow, the medulla oblon- 
gata, and the tubercula quadrigemina, are capable of exciting 
muscular contractions. 
2d. That the cerebral lobes, and the cerebellum are not 
capable of exciting them. Haller and Zinn had formerly noted 
the impassibility (insensibility) of the upper layers of the cere- 
bral lobes; Lorry, that of the corpus callosum; M. Flourens, 
has, for the first time, observed this insensibility in the whole 
of these lobes, in the cerebellum ; and has been the first to fix 
the limit at the tubercula quadrigemina. 
The irritation of a nerve, separated from the nervous centres 
by section or ligature, is confined to the excitement of abrupt 
and partial contractions in the muscles to which this nerve is 
distributed. The nerve, therefore, excites properly only con- 
tractions. 
The spinal marrow being cut successively above the posterior 
enlargement, above the anterior, and near to the occiput: at 
first the animal lost the use of its hind paws, then of its fore 
paws, and next of the trunk; but in all these cases, all these 
parts, the hind and fore paws, as well as the trunk, preserve 
their collective movements, (mouvemens d’ensemble.) 
We ought to add that these movements take place only in 
consequence of external irritations. What has disappeared, is 
first, the co-ordination (consentaneity) of the movements in 
leaping, flying, walking, standing, catching, §c.; and, secondly, 
the volition of these movements. 
What remain, are the contractions and the connexion of 
these contractions in associated movements. The spinal mar- 
row, then, properly ties the muscular contractions, in associations 
(mouvemens d’ensemble) as to volition and the co-ordination of 
these movements that resides elsewhere. 
The irritation of the spinal marrow constantly occasions vio- 
lent convulsions ; its destruction speedily brings on death; but 
this last effect depends on its action on the involuntary move- 
ments. Constantly, the abstraction of one of the tubercula qua- 
drigemina, causes the sight of the opposite eye to be lost. ‘The 
irritation of a tuberculum determines contractions in the oppo- 
site iris; its complete removal abolishes the contractions com- 
pletely. In the tubercula, therefore, the primary principle of the 
action of the iris and of the retina resides. 
In proportion as we cut off the cerebellum, by successive lay- 
ers, the animal loses gradually the faculty of flying or running ; 
then that of walking, and finally that of standing upright. 
A single cerebral lobe being removed, the animal loses imme- 
diately the sight of the opposite eye ; but the contractility of the 
