PHYSIOLOGY OF THE NERVOUS SYSTEM. 
see. After the removal of the deepest layers, 
the animal lost completely the power of stand- 
ing, walking, leaping, or flying. The power 
had been injured by the previous mutilations, 
but now it was completely gone. When placed 
upon his back, he was unable to rise. He did 
not, however, remain quiet and motionless, as 
pigeons deprived of the cerebral hemispheres 
do; but evinced an incessant restlessness, and 
an inability to accomplish any regular or defi- 
nite movement. He could see the instrument 
raised to threaten him with a blow, and would 
make a thousand contortions to avoid it, but 
did not escape. Volition and sensation re- 
mained; the power .of executing movements 
remained; but that of coordinating those move- 
ments into regular and combined actions was lost. 
Animals deprived of the cerebellum are in a 
condition very similar to that of a drunken man, 
so far as relates to their power of locomotion. 
They are unable to produce that combination 
of action in different sets of muscles which is 
necessary to enable them to assume or main- 
tain any attitudes. They cannot stand still for 
a moment; and, in attempting to walk, their 
gait is unsteady, they totter from side to side, 
and their progress is interrupted by frequent 
falls. The fruitless attempts which they make 
to stand or walk are sufficient proof that a cer- 
tain degree of intelligence remains, and that 
voluntary power continues to be enjoyed. 
Rolando had, previously to Flourens, ob- 
served effects of a similar nature consequent 
~ mutilation of the cerebellum. In none 
his experiments was sensibility affected. 
The animal could see, but was unable to exe- 
cute any of the movements necessary for loco- 
motion. ; 
Flourens’ experiments have been confirmed 
by those of Hertwig in every particular, and 
they have been lately repeated with similar re- 
sults by Budge and by Longet. The removal of 
i of the cerebellum appears capable of pro- 
ducing the same vertiginous affection which 
has been already noticed in the case of deep 
injuries to the mesocephale. After the well- 
known experiments of Magendie, of dividing 
either crus cerebelli, the animal was seen to 
roll over on its long axis towards the side on 
which the injury was inflicted. 
The effects of injuries to the cerebellum, ac- 
cording to the reports of the experimenters 
above referred to, contrast in a very striking 
manner with those of the much more severe 
operation of removing the cerebral hemispheres. 
“ Take two pigeons,” says M. Longet; “ from 
one remove completely the cerebral lobes, and 
from the other only half the cerebellum ; the 
next day, the first will be firm upon his feet, 
the second will exhibit the unsteady and un- 
certain gait of drunkenness.” 
Experiment, then, appears strikingly to fa- 
vour the conclusion which Flourens has drawn, 
namely, that the cerebellum possesses the power 
of coordinating the voluntary movements which 
originate in other parts of the cerebro-spinal 
centre, whether these movements have reference 
to locomotion or to other objects. 
That this power is mental, i. e. dependent 
on a mental operation for its excitation and ex- 
722n 
ercise, is rendered probable from the experience 
of our own sensations, and from the fact that 
the perfection of it requires practice. The vo- 
luntary movements of a new-born infant, al- 
though perfectly controllable by the will, are 
far from being coordinate: they are, on the 
contrary, remarkable for their vagueness and 
want of definition. Yet all the parts of the 
cerebro-spinal centre are well developed, except 
the cerebellum and the convolutions of the ce- 
rebrum. Now, the power of coordination im- 
proves earlier and more rapidly than the intel- 
lectual faculties; and we find, in accordance 
with Flourens’ theory, that the cerebellum 
reaches its perfect developement of form and 
structure at a much earlier period than the 
hemispheres of the cerebrum. 
It may be stated as favourable to this view of 
the mental nature of the power by which vo- 
luntary movements are coordinated, that, in 
the first moments of life, provision is made for 
the perfect performance of all those acts which 
are of the physical kind. Thus, respiration 
and deglutition are as perfect in the new-born 
infant as in the full-grown man; and the exci- 
tability of the nervous centres to physical im- 
pressions is much greater at the early age, 
partly perhaps in consequence of the little 
mterference which is received at that period 
from the will. 
That the cerebellum is an organ favourably 
disposed for regulating and coordinating all 
the voluntary movements of the frame is very 
apparent from anatomical facts. No other 
part of the encephalon has such extensive 
connections with the cerebro-spinal axis. It is 
connected slightly indeed with the hemispheres 
of the brain, by the processus cerebelli ad 
testes, but most extensively with the mesoce- 
phale, the medulla oblongata, and the spinal 
cord. Now it is not unworthy of notice that 
its connection with the brain proper is more 
immediately with that part, which may be re- 
garded as the centre of sensation; namely, with 
the optic thalami. This connection of the 
cerebellum with the centre of sensation may 
probably have for its object to bring the mus- 
cular sense to bear upon the coordination of 
movements, in which the individual experience 
of every one shows that that sense must mate- 
rially assist. 
The cerebellum is brought into union with 
each segment of the great nervous centre upon 
which all the movements and sensations of the 
body depend; through the restiform bodies it 
is connected with the medulla oblongata and 
the spinal cord; by the fibres of the pons 
with the mesocephale, and thus with the ante- 
rior pyramids and corpora striata; and through 
the processus e cerebello ad testes with the 
optic thalami. What can be the object of 
these extensive connections? It would be 
difficult to conceive any function for which so 
elaborate a provision would be more necessary, 
than that of regulating and coordinating the 
infinitely complex movements which the mus- 
cular system is capable of effecting; more 
especially when it seems highly probable that 
the antero-lateral columns of the cord, and the 
anterior pyramids and olivary columns supply 
