344 
DR. PHILIP ON THE POWERS OF LIFE. 
cession of contractions and relaxations. Its permanent contraction we have reason 
to believe is always a state of disease* * * § . 
Many of the older physiologists supposed that all the powers of the living animal 
reside in the nervous system. Haller was the first who, in a way that commanded 
general attention, maintained that the muscular power resides in the muscular fibre 
itself, and made experiments for the purpose of establishing this opinion. 
His conclusions however were not generally admitted, and the principle, on which 
the point was argued, could lead to no decision. It was as easy to affirm as to deny 
that the remaining nervous influence is the cause of the power which exists in the 
detached muscle, for it was impossible to separate from the muscular fibre the minute 
extremities of the nerves with which it is blended, and to them it was alleged that it 
owes the power, which for a short time it retains after its separation from the brain, 
spinal marrow and larger nerves. 
The only conclusive means of determining the question appeared to be an appeal 
to such experiments, as are capable of directly ascertaining whether the effect of the 
nervous influence on the muscular fibre be that of maintaining or, analogous to the 
effects of other stimulants, of exhausting its excitability. 
It appears from the 32nd experiment, detailed in my Inquiry into the Laws of the 
Vital Functions that the latter is the case to a degree, that leaves little doubt re- 
specting the result which was confirmed by other experiments, in which I found in 
many trials, that when the powers of the nervous system are destroyed by opium or 
tobacco, the loss of power in the muscles is not proportioned to the degree in which 
the powers of that system are impaired, but simply to the degree in which their con- 
tractions had been excited through it § ; and that the removal of both the brain and 
spinal marrow, which we shall find are the only organs employed in the formation 
of the nervous influence, does not in any degree impair the action of the heart and 
vessels as long as the healthy state of the blood can be maintained by artificial re- 
spiration || . 
From the whole of these experiments it appears that the opinion of Haller is 
correct, that the power of the muscular fibre is not derived from the nervous system, 
but resides in that fibre itself ; a conclusion which we shall find of no small importance 
* See a paper on the Nature of Sleep published in the Philosophical Transactions for 1833 and republished 
in my treatise On the Nature of Sleep and Death. 
f In referring to my Inquiry into the Laws of the Vital Functions the reference is always to the third edition. 
+ When two sets of muscles of the same description were exposed to the action of the same artificial stimu- 
lant, and one of them at the same time to the effects of the nervous influence, it was found that the excitability 
of the latter was most rapidly exhausted ; and this was sometimes the case to so great a degree, that in one 
instance the excitability of the muscles exposed to both was exhausted in half the time required for its ex- 
haustion in those exposed to the artificial stimulant alone. 
§ The fourth edition of my Treatise on Fevers and Inflammations. 
|| Philosophical Transactions for 1815, and my Inquiry into the Laws of the Vital Functions, Part II. 
