ON MUSCULAR IKKIT.VBlLITy. 165 



Comprehending now more fully the nature of the paraljsis which results 

 from depriving limbs of blood, we are in a position to see that whatever in- 

 fluence nerve may exercise in exhausting irritability, when the source of its 

 replenishment is cut off, must necessarily he exercised prior to the accession of 

 the paralysis ; for this form of paralysis affecting the ultimate distributions 

 may be regarded as equivalent to the absence of nerve-tissue ; and under 

 such circumstances the irritable muscular tissue represents the condition and 

 capacity of living muscle freed from nerve-influence. 



It is clear, then, as the terminal distributions of the nerves to the muscles 

 of warm-bloods hecome at once insensible to the stimulus of volition, that the 

 nerve in these cases can have no influence in hastening rigor by exhavisting 

 irritability, and the accession of rigor mortis here must therefore be referred 

 entirely to absence of the blood ; for in these cases we are not even distiirbed 

 by speculations as to the possible influence exercised upon the muscle by 

 the mei-e jjresence of living nerve-tissue in a state of inaction. 



We see, then, that the question with which we started is one capable of 

 solution only by experiments upon cold-bloods carried out in the manner 

 previously indicated ; for in these only is it possible for nervous influence to act 

 uponmuscidar irritability in the absoice of the blood, and in. these tor a limited 

 period only, but, nevertheless, sufficiently long to prove whether or not the 

 mere presence of inactive living nerve climinishes muscular irritability, or 

 whether the loss of irritability is appreciable only when the muscle is either 

 controlled or induced to contract by nervous influence. Space will not permit 

 me to recite the complicated experiments by which the necessary conditions 

 were achieved, and I must content myself in this place by briefly stating the 

 deductions arrived at. 



1. Mere presence of living nerve in a state of inaction neither hastens nor 

 retards the accession of rigor, and therefore has no influence on irritability. 



2. The condition of nerve concerned in simple muscular control and in 

 contraction leads to earlier rigor mortis, and therefore possesses the power of 

 exhausting irritability. 



Leaving now this aspect of the question, we proceed to inquire what 

 evidence do we possess that muscular irritability is capable of abnormal ex- 

 altation in the absence of nerve, or in those uncontrolled powerless states of 

 the muscular system which, from the absence of volitional impulse, are equi- 

 valent thereto. 



First, we have the fact that if one limb of a frog be paralyzed by sec- 

 tion of its nerve, after a certain jyeriod has elcqised it will be found more 

 susceptible to the various forms of external stimulation than the other limb ; 

 and if such an animal be killed or happen to die, the limb in which the nerve 

 is intact «dll lose its irritability, and pass into the state of rigor, long prior 

 to the limb the nerve of which has been divided. 



Dr. Radclrffe remarks, " Many experiments might be mentioned, all of 

 which seem to show more or less clearly that the disposition to convulsive 

 muscular contraction is inversely related to the supply of nervous influence 

 to the muscles." Vide ' Lancet,' 1863, vol. i. p. 321. This is in the main cor- 

 rect, but it renders no support to the inhibitory theory of nervous action as 

 propounded by its talented author. The readiness tvith which muscle contracts 

 is cdwuys in direct proportion to the amount of force accumulated in its struc- 

 ture, or, in other words, to its irritability. It is not that the absence of nerve 



past restoration? Is there any intermediate tissue differing from nerve or muscle -wjiich 

 forms the bond of union between them ? 



