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Dr. B. Ward Richardson on Muscular [May 29, 



then with what infinite facility the muscular irritability of the heart, in 

 all its parts, is excited, for a moment only, to be permanently destroyed. 

 They would learn that if blood be not passing through the muscular 

 structure concurrently with the exciting agent, they could not more 

 effectually arrest function than by the very method they have adopted to 

 sustain it. 



The influence of the continuous current on muscular irritability was 

 introduced by the author, together with a special reference to the first 

 experiments of Aldini on the bodies of malefactors who had been recently 

 executed ; and it was shown from Aldini's most noted experiment how 

 largely the phenomena of motion he induced in a dead man, and the 

 recital of which caused so much sensation in the year 1803, was due, not 

 to the galvanism, but to the circumstance that the dead body had been 

 exposed for the hour after death, and before the experiments com- 

 menced, to the action of cold two degrees below freezing-point. On 

 the whole the continuous current acts on muscular fibre after the manner 

 of heat. If the muscle, recently dead, be exposed to cold, the current, 

 when sufficient, restores for a limited period the irritability, and finally 

 destroys it by inducing persistent contraction ; if the muscle, recently 

 dead, be left at its natural temperature, the current simply shortens the 

 period of irritability by quickening contraction. 



Abstraction and Supply of Blood. 



Under this head the author first considered the effect of abstraction 

 of blood from the living muscular fibre. He showed that when the flow 

 of blood was very rapid, there was invariably a given period of muscular 

 excitation. In sheep killed in the slaughterhouse he found that this 

 muscular excitement occurred at the time when the proportion of blood 

 removed from the animal was equivalent to about the 320th part of the 

 weight of the animal. The increased irritability passes rapidly into 

 general convulsion without consciousness, and, as a rule, ceases for a time 

 with a temporary cessation of further loss of blood. After this the 

 irritability remains, if the bleeding be arrested altogether, and can be 

 called into action by any external stimulus, although it is rarely spon- 

 taneously manifested when the vessels are left divided and open. After 

 an interval of one or two minutes there is a recurrence of loss of blood, 

 followed by a muscular excitement which marks the moment of systemic 

 death. The breathing and circulation cease, but the voluntary muscles 

 retain their irritability for several minutes, until they undergo per- 

 manent contraction ; indeed they retain their irritability under the influ- 

 ence of cold and lose it under the influence of mechanical motion, heat, 

 or electricity as markedly as when death has been produced without 

 abstraction of blood. 



The fact of the two stages of exalted muscular irritability during 

 abstraction of blood is important, as indicating the two different tensions 



