712 
columns of the cord, partly through the deep 
fibres of its great commissure, the pons Varolii, 
which interlace freely with the fibres of the 
anterior pyramids, vesicular matter being in. 
_ terposed, and partly through those portions of 
the restiform bodies which penetrate the antero- 
lateral columns of the spinal cord. It asso- 
ciates and harmonizes the movements of the 
trunk, and especially those of the lower ex- 
tremities, for locomotion, through those por- 
tions of the restiform bodies which are con- 
tinued with the posterior columns of the cord. 
The crossed influence of deep lesion of either 
hemisphere of the cerebellum is diffieult to 
explain in the absence of any peers decus- 
sation of the restiform bodies. The connection 
of the deep fibres of the pons, however, with 
the anterior pyramids in the mesocephale does 
afford some explanation. If, for instance, the 
left cerebellar hemisphere be the seat of lesion, 
these fibres will be affected, and they may in- 
fluence the fibres of the left pyramid, which 
again will affect the right half of the cord and 
the right side of the body. Those fibres of 
the restiform bodies which incorporate them- 
selves with the antero-lateral columns, are 
doubtless too few to produce much influence. 
ABNORMAL ANATOMY OF NERVES AND NER- 
vous CENTRES.—The great space already occu- 
pied by this article obliges me to compress into 
as small a compass as possible the observations 
which I propose to make under this head. 
An interesting preliminary question is to de- 
termine to what extent nervous matter is capa- 
ble of being regenerated, when any solution of 
its continuity may have occurred. In nerve it 
has long been proved that such regeneration is 
capable of taking place. If the nerve be 
simply divided, without loss of substance, 
union may take place immediately ; but if a 
piece of it have been cut away, a considerable 
period must elapse before its complete restora- 
tion. This was satisfactorily proved by Dr. 
Haighton’s* experiments, in which he found 
that the function of the inferior laryngeal nerve 
in dogs was restored six months after division 
of the vagus, but with altered tones. Tiede- 
mann divided in a dog the nerves of the fore- 
foot and leg, and at the expiration of eight 
months observed that sensation and motion re- 
turned ; after twenty-one months the sensi- 
tive power had increased considerably, and 
at length the dog regained the complete use of 
his foot. Schwann divided both sciatic nerves 
of a frog, in the middle of both thighs: imme- 
diately after the operation the frog’s movements 
were very imperfect; after a month it had 
gained some power; but in three months it 
leaped as well as if no division had taken place. 
The sensibility of the foot, which was destroyed 
by the section, became nearly entirely restored ; 
and irritation of the nerve with a needle above 
the cicatrix produced strong contractions in the 
muscles supplied from the nerve below the 
wound. On examination with the microscope, 
Schwann found that the cicatrix consisted of 
true nerve fibres disposed in their usual way.t 
* Phil. Trans, 1795. 
t Quoted in Miiller’s Physiology. 
NERVOUS SYSTEM. (Nervous Centres. Asnormat Anatomy.) 
Miiller mentions the interesting fact of the 
return of some degree of sensation in the flaps — 
of skin used for the Taliacotian operation for 
new nose, as an argument in favour of the re- 
production of nerves. Dieffenbach, however, 
who has had so much expetience in these ope. 
rations, states that the return of sensibility 
only very imperfect, which is to be expe te 
since the divided extremities of the same fib 
cannot re-join, except in very small number 
The evidence of restoration of ; 
divided nerves in the human subject is in 'p 
fect, although not op to what has be 
above stated. Gruithuisen’s observations 
the consequences of an accidental division 
the dorsal nerve of the thumb in his own p 
son are sufficiently conclusive. Eight mon 
after the division, although the sensation | 
returned, it was so imperfect that the mil 
could form no conception of the precise px 
stimulated, as if the isolation of the fibres 
necessary to exact sensation had been 
stroyed in the cicatrix, or as if the fibres of 
peripheral portion of the nerve had not unit 
with the corresponding ones in its central po 
tion. Mr. Earle relates a case in which a p 
of the ulnar nerve was cut out; at the end 
four years the little finger was useless, and 
sensations very imperfect. é 
Indeed there is much difficulty in dra 
conclusions from the restoration or non-rest 
tion of function after division of nerves, for 
artificial disposition of the cut extremities ¥ 
insure the corresponding fibres meeting. As 
sitive fibre may be joined to a motor, and t 
the office of both would be neutralised ; or 
ferent sensitive fibres might unite, from w 
doubtless some confusion as to the natu 
position of the impression would ensue. 
The microscopic examinations of Seinrt 
Hermann, Nasse, and Klencke have rend: 
certain that true nerve-fibres are 
the cicatrix of a divided nerve. Nasse states 
they are smaller than the natural size; | 
he has likewise pointed out an interes 
fact, in the decrease of size of the fibres 
peripheral segment of the nerve as comp 
with those of the central segment, showi 
a certain degree of atrophy takes place im 
portion of the nerve, even after it has bes 
parated for a short period from its conn 
with the nervous centre, This author | 
Saw sensation and motion return, althor 
kept the animals for three quarters of a 
Perhaps this was owing to his having ret 
large portions of the nerves he operated 1 
With respect to the reproduction of sol 
of continuity in the nervous centres, wh 
is known must be viewed as unfavourable 
supposition that perfect restoration of 
oa takes place. If the brain or spin 
wounded, union will take place; & 
not appear from Arnemann’s observati¢ 
from Flourens’s that the uniting subs 
true nervous matter, Further researche 
much needed upon this interesting subject. 
Abnormal anatomy of the spinal cord a 
membranes.—The membranes of the sf 
'o i 
are liable to those morbid changes which | 
_: 
tine 
