721N 
posture through the influence of the spinal 
cord, but, immediately this organ has been 
removed, the limbs fall apart from the loss of 
the controlling and co-ordinating influence of 
the nervous centres. And careful examination 
of the muscles in such a case as this will show 
that the molecular phenomena which charac- 
terise passive contraction continue in the mus- 
cular fibres. The state of rigor mortis, which 
is analogous to that of tone, comes on just as 
readily in animals which have been deprived 
of the brain and spinal cord, as in those 
in which these centres have been undisturbed 
before death. In short, healthy nutrition sup- 
plies all the conditions necessary for the main- 
tenance of tone or passive contraction ; nor is 
the spinal cord (although itself healthy) able to 
preserve the tense condition of the muscles, if 
they are not well nourished. 
These remarks apply equally to Dr. Hall’s 
doctrine, that the spinal cord is a direct source 
of irritability to the muscular system. The 
same arguments whith prove that tone is not 
derived from it are of equal weight with refe- 
rence to irritability. : 
It cannot be admitted as an argument in 
favour of the view which derives muscular irri- 
tability from the spinal cord, that muscles lose 
their firmness and waste, when they have been 
for some time separated from their proper ner- 
vous connections. They suffer, in this way, 
merely for want of a proper amount of exercise, 
which they cannot obtain in consequence of 
the influence of the will being cut off from the 
limb. If, however, the paralysed limb be ex- 
ercised artificially, as by the galvanic current, 
their nutrition and their plumpness may be 
preserved. For this important observation we 
are indebted to Dr. John Reid, who likewise 
called attention to the confirmatory fact, that, 
in those palsies with which there is combined 
more or less of irritation of the nervous centre, 
the muscles do not suffer so much in their 
nutrition, in consequence of the exercise they 
undergo in the startings so frequently excited in 
them by the central irritation. This is not 
unfrequently seen in cases of paraplegia from 
irritant disease of the spinal cord. 
The supposition that the spinal cord might 
be the source of irritability to the muscles led 
Dr. Hall to the very extraordinary inference, 
that in hemiplegic paralysis, in which the in- 
fluence of the brain is cut off from certain 
muscles, while that of the cord remained, the 
irritability of those muscles becomes augmented. 
He arrives at this conclusion by the following 
line of argument: assuming the cord to be the 
source of the irritability of the muscles, the 
brain may then evidently be looked upon as 
the exhauster of that irritability in the volun- 
tary actions; if, then, the influence of the 
brain be cut off, it naturally follows that, as the 
great agent of exhaustion has lost its power, 
the irritability, which is ever, as it were, flow- 
ing from the cord, will accumulate in the 
muscles. From numerous experiments I am 
enabled to state that in nearly all the cases of 
hemiplegic paralysis from cerebral lesion there 
is no evidence of any augmentation of the 
PHYSIOLOGY OF THE NERVOUS SYSTEM. 
irritability of the muscles of the palsied limbs. 
If the readiness with which they will respond 
to the galvanic stimulus be taken as a test, 
it may on the other hand be stated very 
confidently that there is evidence of the di- 
minution of the irritability of the paralysed 
muscles, for in nearly all these cases the same 
current being passed through both sound and 
palsied limbs at the same time, the latter have 
contracted either not at all or with very little 
power as compared with the healthy limbs. 
But there are exceptions to this: in some 
cases (and only in those in which there is 
more or less rigidity of the paralysed muscles) 
these muscles respond to the galvanic stimulus 
with more force and readiness than the sound 
ones. In these cases the palsied muscles are 
kept in a state of excitement by some irritant 
disease within the cranium, and this constant 
condition of more or less active contraction 
augments the nutrition, and therefore the irri- 
tability of the muscles. 
It seems, however, most probable that in all 
the cases of paralysis, the excitability of the 
muscles to the galvanic stimulus is d 
not so much upon any change in the condition 
of the muscles themselves as upon the state of 
the nerves. If the nervous force in the nerves 
on the palsied side be depressed, the galvanic 
stimulus will produce little or no effect upon 
the muscles of that side, whilst those of the 
other side will be distinctly excited: butshould 
the nerves participate in any excitement 
gated to them from disease within the craniu 
as in red softening, or an irritating tumor, or 
contracting cyst, they will then respond to the 
galvanic current more readily than those of the 
opposite side.* . 
ca 
I have thus endeavoured to show that the 
spinal cord is a centre of nervous actions, 
tal and physical, to all parts which derive nerve 
Jrom it, the mental actions, however, requiring 
its association with the brain. Whatever phy- 
sical nervous actions occur in parts whose 
nerves are spinal, must be referred to the cord 
alone; and whatever mental nervous actio’ 
occur through the agency of spinal nerves must 
be referred to the cord in conjunction with t 
brain. 
Of the office of the columns of the cord.— 
shall now inquire whether the parts into whi 
the anatomist can divide the spinal cord 
special functions. These parts are, on € 
side of the median plane, an antero-lateral S 
lumn and a posterior column. It has been 
very prevalent opinion that the antero-t: 
column corresponds in function with the ant 
rior roots of the spinal nerves, and that the pos 
terior column corresponds with the posteri 
roots. This doctrine might have had a goo 
foundation if it could be proved that the poster 
or sensitive roots were implanted solely in tt 
* I have discussed this subject more at large if 
a paper presented to the Royal Medico-Chirargic 
Society in June last, and which will appear in th 
ree volume of its Transactions. Aug 
