470 INDUCTION. 



Sequard found to be the fact. The galvanic experiment was 

 tried with charges of very various degrees of strength ; and the 

 more powerful the charge, the shorter was found to be the dura- 

 tion of rigidity, and the more speedy and rapid the putrefaction. 

 In the experiment in which the charge was strongest, and the 

 muscular irritability most promptly destroyed, the rigidity only 

 lasted fifteen minutes. On the principle, therefore, of the 

 Method of Concomitant Variations, it may be inferred that the 

 duration of the rigidity depends on the degree of the irrita- 

 bility ; and that if the charge had been as much stronger than 

 Dr. Brown-Sequard's strongest, as a stroke of lightning must 

 be stronger than any electric shock which we can produce 

 artificially, the rigidity would have been shortened in a corre- 

 sponding ratio, and might have disappeared altogether. This 

 conclusion having been arrived at, the case of an electric shock, 

 whether natural or artificial, becomes an instance in addition 

 to all those already ascertained, of correspondence between the 

 irritability of the muscle and the duration of rigidity. 



All these instances are summed up in the following state- 

 ment : " That when the degree of muscular irritability at the 

 time of death is considerable, either in consequence of a good 

 state of nutrition, as in persons who die in full health from 

 an accidental cause, or in consequence of rest, as in cases of 

 paralysis, or on account of the influence of cold, cadaveric 

 rigidity in all these cases sets in late and lasts long, and putre- 

 faction appears late, and progresses slowly :" but " that when 

 the degree of muscular irritability at the time of death is slight, 

 either in consequence of a bad state of nutrition, or of exhaus- 

 tion from over- exertion, or from convulsions caused by disease 

 or poison, cadaveric rigidity sets in and ceases soon, and 

 putrefaction appears and progresses quickly." These facts 

 present, in all their completeness, the conditions of the Joint 

 Method of Agreement and Difference. Early and brief rigidity 

 takes place in cases which agree only in the circumstance of a 

 low state of muscular irritability. Eigidity begins late and 

 lasts long in cases which agree only in the contrary circum- 

 stance, of a muscular irritability high and unusually prolonged. 

 It follows that there is a connexion through causation between 

 the degree of muscular irritability after death, and the tardiness 



