468 INDUCTION. 



in no circumstance, directly connected with the muscles, except 

 that these have just been subjected to exhausting exercise. 

 Under the canon, therefore, of the Method of Agreement, it 

 may be inferred that there is a connexion between the two 

 facts. The Method of Agreement, indeed, as has been shown, 

 is not competent to prove causation. The present case, how- 

 ever, is already known to be a case of causation, it being cer- 

 tain that the state of the body after death must somehow 

 depend upon its state at the time of death. We are therefore 

 warranted in concluding that the single circumstance in which 

 all the instances agree, is the part of the antecedent which is 

 the cause of that particular consequent. 



4thly. In proportion as the nutrition of muscles is in a 

 good state, their irritability is high. This fact also rests on 

 the general evidence of the laws of physiology, grounded on 

 many familiar applications of the Method of Difference. Now, 

 in the case of those who die from accident or violence, with 

 their muscles in a good state of nutrition, the muscular irrita- 

 bility continues long after death, rigidity sets in late, and 

 persists long without the putrefactive change. On the contrary, 

 in cases of disease in which nutrition has been diminished for 

 a long time before death, all these effects are reversed. These 

 are the conditions of the Joint Method of Agreement and 

 Difference. The cases of retarded and long continued rigidity 

 here in question, agree only in being preceded by a high state 

 of nutrition of the muscles ; the cases of rapid and brief 

 rigidity agree only in being preceded by a low state of mus- 

 cular nutrition ; a connexion is therefore inductively proved 

 between the degree of the nutrition, and the slowness and pro- 

 longation of the rigidity. 



5thly. Convulsions, like exhausting exercise, but in a 

 still greater degree, diminish the muscular irritability. Now, 

 when death follows violent and prolonged convulsions, as in 

 tetanus, hydrophobia, some cases of cholera, and certain 

 poisons, rigidity sets in very rapidly, and after a very brief 

 duration, gives place to putrefaction. This is another ex- 

 ample of the Method of Agreement, of the same character 

 with No. 3. 



