EXAMPLES OF THE FOUR METHODS. 467 



of the Method of Difference, requiring no comment. A further 

 and very important corroboration was obtained by the same 

 method. When the animal was killed, not shortly after the 

 section of the nerve, but a month later, the effect was reversed ; 

 rigidity set in sooner, and lasted a shorter time, than in the 

 healthy muscles. But after this lapse of time, the paralysed 

 muscles, having been kept by the paralysis in a state of rest, 

 had lost a great part of their irritability, and instead of more, 

 had become less irritable than those on the healthy side. This 

 gives the A B C, a b c, and B C, b c, of the Method of Dif 

 ference. One antecedent, increased irritability, being changed, 

 and the other circumstances being the same, the consequence 

 did not follow ; and moreover, when a new antecedent, con 

 trary to the first, was supplied, it was followed by a contrary 

 consequent This instance is attended with the special advan 

 tage, of proving that the retardation and prolongation of the 

 rigidity do not depend directly on the paralysis, since that was 

 the same in both the instances ; but specifically on one effect 

 of the paralysis, namely, the increased irritability ; since they 

 ceased when it ceased, and were reversed when it was reversed. 

 2ndly. Diminution of the temperature of muscles before 

 death increases their irritability. But diminution of their tem 

 perature also retards cadaveric rigidity and putrefaction. 



Both these truths were first made known by Dr. Brown- 

 Sequard himself, through experiments which conclude accord 

 ing to the Method of Difference. There is nothing in the 

 nature of the process requiring specific analysis. 



Srdly. Muscular exercise, prolonged to exhaustion, dimi 

 nishes the muscular irritability. This is a well-known truth, 

 dependent on the most general laws of muscular action, and 

 proved by experiments under the Method of Difference, con 

 stantly repeated. Now it has been shown by observation that 

 overdriven cattle, if killed before recovery from their fatigue, 

 become rigid and putrefy in a surprisingly short time. A 

 similar fact has been observed in the case of animals hunted to 

 death; cocks killed during or shortly after a fight; and 

 soldiers slain in the field of battle. These various cases agree 



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