———————— 
MUSCULAR MOTION. 
description that though contractility remained, 
it was diminished proportionally to the wasting, 
in the limbs that had not been exercised. 
The results of this admirably devised experi- 
ment cannot possibly be reconciled with the 
opinion that the spinal cord has any necessary 
or immediate influence in conferring contracti- 
lity on muscles—that it is the source whence 
that property is derived. On the contrary, they 
show in a manner that admits of no dispute 
that both coutractility and nutrition have been 
preserved together by the continued activity of 
the property existing in the fully developed 
organ at the period when the experiment was 
begun ; and hence it is plain, and conformable 
to all analogy, that contractility is a property 
depending for its integrity on a healthy state of 
nutrition, which in its turn requires for its 
support the due exercise of the property it 
_ coniers. 
It might, perhaps, be argued by one dis- 
‘posed to uphold the electrical hypothesis of 
the nervous influence and muscular power, 
that in the foregoing experiments the galvanism 
supplied the place of the intercepted nervous 
communication, by directly furnishing the 
muscles with the endowment of contractility ; 
and it is not easy to meet the objection by any 
decided proof to the contrary. It would be 
very difficult to induce oft-repeated contractions 
in a paraly-ed muscle by any other than elec- 
trical agency; but the refutation of this view 
will be found in the general arguments against 
the identity of the nervous influence with any 
form of electricity. 
Viewed by the light of this and other allied 
experiments, the variation found in the state of 
nutrition of paralyzed limbs is easily accounted 
for. In cerebral paralysis: the muscles are still 
subject to contraction in obedience to reflected 
‘Stimuli through the spinal cord, while in the 
complete spinal palsy and that arising from 
disease of the nerves, they are never excited to 
action; whence their firmness in the former 
compared with their impoverishment in the 
latter case. In the paralysis of the lower limbs 
So graphically described by Pott, and resulting 
from disease propagated to the cord from the 
vertebre, the early symptoms are those of 
irritation, and consist rather of irregular con- 
tractions, probably in part reflex, and which 
the patient is unable to control, than of any 
diminution of actual power in the limbs; and 
it is constantly remarked that in this stage there 
is no loss of size in the affected parts, but 
rather that in the midst of a general emaciation 
consequent on the patient’s confinement, these 
limbs retain their fullness, and even appear 
hypertrophied. Should the malady advance to 
disorganization of the cord, the muscles cease 
to be excited. They become dead to all stimuli 
_ except such as are topically applied, and being 
hever so stimulated, soon become flabby and 
wasted. Thus it would appear that the spinal 
cord in cerebral paralysis serves to ree up 
contractility in the muscles, not by supplying 
them with it, as from a source, but by exhaust- 
ing them through the contractions it excites. 
It is not a charger but an exhauster through its 
521 
nerves ; and as exhaustion alternating with re- 
accumulation is necessary for healthy nutrition, 
and healthy nutrition induces contractility, it 
becomes in such cases an important though 
indirect agent in the maintenance of that pro- 
perty in the muscles. ‘There can be little doubt 
that if muscles completely cut off from the 
nervous centres were submitted to galvanic 
agency at frequent intervals, they would not 
decrease in size, and might, if already atrophied, 
be even augmented in bulk and power; and 
ds some of the vaunted successes obtained 
y galvanism and electricity may be explained 
in this manner. 
There appears to be no argument nor esta- 
blished fact on the other side which invalidates 
the experiment of Dr. Reid, or which does not 
admit of being explained on the ground which 
that experiment substantiates; and the whole 
question 1s still further cleared by the singular 
circumstance that has been often adduced, that 
foetuses born without brain or cord may have 
their muscular system developed and active. 
If, to what has now been advanced, there 
be added the evidence before adduced, that 
this is a property inherent in the very structure 
of muscle, and that it is capable of being 
exerted therein independently of all communi- 
cation with other tissues, it will probably no 
longer remain doubtful that it is a property 
belonging to muscle as a tissue, and that it 
only requires for its perfection that nutrition 
should be perfect. Whatever interrupts nutri- 
tion interferes with it, and it matters little 
whether such interruption arise from the want 
of its own exercise or from deficiency of arterial 
supply, arising from causes either local or 
general. Inertness of a muscle, whether the 
consequence of diseased nerves or otherwise, 
will be attended with more or less atrophy and 
weakness, according to its degree, and to that 
alone. 
For full information concerning the varieties 
in the intensity of this power, and in its dura- 
bility in muscles after systemic death or after 
their removal from connexion with the nervous 
and vascular systems, the reader is referred to 
the article InRITaBILiTyY. 
I would merely remark in corroboration of 
the views there maintained, that in the animal 
series the size of the elementary fibres and the 
consequent amount of their vascular supply, 
independently of the more or less arterial 
quality of the blood, is accurately proportioned 
to their irritability. Thus Birds, whose irrita- 
bility is most exalted and most evanescent, 
have the smallest fibres and the most richly 
supplied with blood, while Reptiles, Fish, and 
Crustacea, in which the irr.tability is most 
enduring, have fibres of large dimensions and 
provided with a vascular web of small com- 
parative size (fig. 286, art. Muscre). The 
same is true as regards the heart compared 
with the voluntary muscles. 
b. Of the stimuli of muscle—The stimuli 
which induce contraction have been classed 
into remote and immediate. Properly speaking, 
the remote stimuli are stimuli to the nerves and 
not to the muscles: they cause a change in the 
