166 REPORT— 1866. 



produces a greater proclivity to contraction in the mnsele, but that tLe muscle 

 in the absence of nerve can accumulate the force on which irritability depends. 

 In all the experiments in which muscle contracts more readily in the absence 

 of nerve, the element time is an important ingredient ; for if its influence be 

 excluded, the opposite condition, viz. tJuif 7in(scJe contracts more readily in the 

 presence of nerve-injluence, is the normal law, as I hope shortly to show. 



To the fact that muscle relieved from nerve-influence acquires additional 

 contractile energy I add the further important observation, that it retains its 

 irritability not uufrequently for days after its fellow has passed into the 

 state of rigor mortis. 



The experiment just cited also tends to show that the presence of nerve in 

 action keeps down muscular irritability and initiates rigor mortis, as before 

 demonstrated ; for we see that when blood is circulating equally thi-ough two 

 limbs, the irritability of the one cannot be maintained at the same standard in 

 the presence of the nerve. If rigor mortis could be regarded as a contraction, 

 it might be supposed, in accordance with old notions, that the dying nervous 

 system had something to do \\'ith its premature induction ; but as rigor is a 

 mere setting of the muscular tissue, this idea has not a shadow of probability * ; 

 besides the rigor will supervene in the limbs simultaneously in cases in which 

 the death of the animal succeeds immediately the section of the nerve. 



Dr. Brown Sequard has fui-nished us with a most beautiful experiment which 

 bears intimately upon the present question, and which also has been used by 

 Dr. Eadcliffe to siipport the proposition, " that the state of muscular relaxation 

 is more readily disturbed by contraction, and tliat the contraction itself is more 

 powerful when the muscles are receiving a diminished supply of nervous in- 

 fluence." The experiment is as foUows : — Two frogs (A and B) are taken and 

 their spinal cords divided low down in the ccr^ical region so as to remove the 

 lower limbs from the control of the brain and medulla oblongata. In such 

 cases the reflex (?) contractions induced by pinching the toes are capable of 

 raising heavier weights than could be raised by the hind limbs when the 

 frogs were in their normal condition. Thus they raised before division of the 

 cord GO grammes. Immediatdy after division A raised 20 and B 10 grammes 

 only. In five minutes A raised 45 grammes and B only 30 ; thus they pro- 

 ceed increasing rajndly in power, till in four hours A can sustam 140 grammes 

 and B 130. At the cud of twenty-four hours they are found to have reached 

 their maximum point, \\z. 150 and 140 grammes respectively. 



The first point worthy of notice in this important experiment is, that a 

 degree of shock was produced by the operation in frog A measured by a loss 

 of power equivalent to 40 grammes, and in frog B to 50 grammes. This 

 diminished power would be entireh" due to loss of nervous force and muscular 

 irritability, chiefiy the former, — partly the direct result of severe injuiy to the 

 nervoTis centres, and partly of loss of blood and depression of the heart's 

 action. 



Secondly, it would be at this period, wheu A could raise but 20 and B 10 

 grammes onlj' while suffering from shock, that the nervous influence would 

 he at its lowest ebb ; and if the muscles possessed a fail' amount of irritability 

 (which they certainly do) after such operations, this should be, if Dr. Rad- 

 cliife's views are correct, the period at which the (jrealcd weights conld be 

 raised ; for the period of profoundest nervous shock admitting of neural ex- 

 citement of the muscles would be the one in which the miuimum degree of 

 nervous influence exists. 



'' See mj paper on that subject in Brit. Assoc. Report for 1865, Trans, of Sfect. p. 109. 



