EXAMPLES OF tHPi FOtTR METHODS. 



27^ 



destroyed, the rigidity only lasted 

 fifteen minutes. On the principle, 

 therefore, of the Method of Concomi- 

 tant Variations, it may be infened 

 that the duration of the rigidity de- 

 pends on the degree of the irritability ; 

 and that if the charge had been 

 aa much stronger than Dr. Brown - 

 S^quard'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 corresponding 

 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 corre- 

 spondence between the irritability 

 of the muscle and the duration of 

 rigidity. 



All these instances are summed iip 

 in the following statement : — " That 

 when the degree of muscular irrita- 

 bility at the time of death is consider- 

 able, 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 putrefaction appears late, 

 and progresses slowly ; " but " that 

 when the degree of muscular irrita- 

 bility at the time of death is slight, 

 either in consequence of a bad state 

 of nutrition, or of exhaustion 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. Rigidity begins 

 late and lasts long in cases which 

 agree only in the contrary circum- 

 stance, of a muscular irritability high 

 *nd "Tiusually prolonged. It follows 



that there is a connection through 

 causation between the degree of mus- 

 cular irritability after death and the 

 tardiness and prolongation of the cada- 

 veric rigidity. 



This investigation places in a strong 

 light the value and efl&cacy of the 

 Joint Method. For, as we have 

 already seen, the defect of that 

 Method is, that, like the Method of 

 Agreement, of which it is only an 

 improved form, it cannot prove causa- 

 tion. But in the present case (as in 

 one of the steps in the argument 

 which led up to it) causation is already 

 proved, since there could never be 

 any doubt that the rigidity altogether, 

 and the putrefaction which follows it, 

 are caused by the fact of death. The 

 observationsand experiments on which 

 this rests are too familiar to need 

 analysis, and fall under the Method 

 of Difference. It being, therefore, 

 beyond doubt that the aggregate 

 antecedent, the death, is the actual 

 cause of the whole train of conse- 

 quents, whatever of the circumstances 

 attending the death can be shown to 

 be followed in all its variations by 

 variations in the effect under investi- 

 gation, must be the particular feature 

 of the fact of death on which that 

 effect depends. The degree of muscu- 

 lar irritability at the time of death 

 fulfils this condition. The only point 

 that could be brought into question 

 would be whether the effect depended 

 on the irritability itself, or on some- 

 thing which always accompanied the 

 irritability : and this doubt is set at 

 rest by establishing, as the instances 

 do, that by whatever cause the high 

 or low irritability is produced, the 

 effect equally follows ; and cannot, 

 therefore, depend upon the causes of 

 irritability, nor upon the other effects 

 of those causes, which are as various 

 as the causes themselves, but upon 

 the irritability solely. 



§ 5. The last two examples will 

 have conveyed to any one by whom 

 they have been duly followed so clear 

 a conception of the use and practical 



