404 THE TISSUES. 



flexors, however, being usually more contracted than the exten- 

 sors, flexing the fingers on the palm, and the forearm on the arm, 

 and closing the mouth if the lower jaw had previously fallen. It 

 is equally intense even in muscles paralyzed by hemiplegia, pro- 

 vided they have not become much atrophied. 



The period elapsing after death before its supervention, and its 

 duration, are variable. It usually occurs within seven hours, and 

 continues from twenty-four to thirty-six hours. But twenty or even 

 thirty hours may elapse before it supervenes, and it may be pro- 

 longed through several days. Its departure is immediately followed 

 by decomposition. When early developed, it lasts but a short time, 

 and vice versa. Any cause which has exhausted the muscular energy 

 before death, causes the rigor mortis to come on and to pass off 

 sooner as a protracted disease, or violent efforts. Indeed, power- 

 ful stimulation of the muscles by electrical currents, immediately 

 after death, also produces the same effect. The following results 

 were obtained by M. Brown-Se'quard, who experimented on four 

 rabbits, reserving a fifth for comparison : 



1. Not electrized; rigidity occurred in 10 hours, and remained 192 



hours. 



2. Feebly electrized; rigidity occurred in 7 hours, and remained 144 



hours. 



8. Somewhat more electrized; rigidity occurred in 2 hours, and re- 

 mained 72 hours. 



4. Still more strongly electrized; rigidity occurred in 1 hour, and 



remained 20 hours. 



5. Submitted to a powerful current; rigidity occurred in 7 minutes, 



and remained 25 minutes. 



In animals hunted to death, the rigidity comes on very early, and 

 lasts bat for a short time. 



On the other hand, M. Brown-Sequard found that the rigor 

 mortis is deferred by injecting the muscles with fresh blood, after 

 death. Stannius also found it to occur even in living animals, if 

 the supply of blood to a group of muscles is entirely cut off. After 

 death from typhus, the limbs sometimes stiffen within fifteen to 

 twenty minutes. It also occurs rapidly in infants, and in old 

 people. 



It should, however, be remembered that in certain states of the 

 muscular and nervous systems, a tetanic rigidity immediately en- 



