

THE RIGOR MORTIS. 145 



sickly, weak, and emaciated bodies, in new-born infants, and in ani- 

 mals exhausted by over-fatigue, it comes on quickly, is weak in its 

 effects, and disappears most rapidly. It is independent of any influ- 

 ence from the nervous centres, for these may be destroyed without 

 preventing its occurrence ; and it occurs even in paralytic limbs, 

 when the muscles are not too much impaired in their nutrition. A 

 form of muscular rigidity can be induced in a living animal by stop- 

 ping the circulation through a limb ; and the true rigor mortis itself 

 may be completely removed by injecting defibrinated arterial blood 

 into the arteries of a dead limb. If this be done within a short time 

 after death, the irritability of the muscles is also restored : this effect 

 has been kept up for forty-one hours, the opposite limb in the mean- 

 time beginning to putrefy. It would seem that the rigor mortis 

 occurs more slowly, is most marked, and lasts the longest, in direct 

 proportion to the previous amount of nutritive activity and irritability 

 in the muscle. It was stated by Hunter that it did not occur in cer- 

 tain cases of death by lightning ; but it has been observed in the body 

 of a dog killed by electrical shock : it has also been said to be absent 

 after death from severe injuries or violent emotions ; ,but in such cases 

 it may have come on very quickly, and as rapidly disappeared. It 

 often begins when the body is still warm. It occurs in drowned per- 

 sons, and also in the corpse when immersed in water after death. It 

 comes on sooner in cold weather, and in parts exposed to the air. In 

 the human body it first commences about the muscles of the lower jaw 

 and neck, then proceeds to the upper limbs, next to the trunk, and 

 lastly to the lower limbs ; it passes off in the same order. The rigid- 

 ity is completely destroyed by forcible extension ; but if the extension 

 be used before it is complete the muscle may again become rigid. 



By some the rigor mortis is regarded as the result of a vital con- 

 traction, perhaps the last evidence of tonicity; but it commences when 

 the contractility is already enfeebled; and even paralyzed muscles 

 become rigid. Moreover, the state of rigidity itself differs from that 

 of the vital contraction of a muscle, by its uniform and persistent 

 character, and by the diminished cohesion or strength, the smaller ex- 

 tensibility, and the less perfect elasticity or resilient property of the 

 rigid muscular substance, and particularly by the total cessation of all 

 electrical currents in it. By others it has been attributed to a molec- 

 ular change in the sarcous elements of the fibrilbe, dependent on the 

 stagnation of the blood-current ; to a sort of coagulation or setting of 

 the muscle-fibrin of the sarcous substance of the fibrillse, compared to 

 the coagulation of the blood (see p. 72) ; to the coagulation of a fibrin- 

 ous material between the fibrillse of each fibre (Brucke) ; or, lastly, 

 to chemical changes giving rise to the production of an acid or alka- 

 line fluid, which stimulates the still contractile muscle. According to 

 this latter view, the rigor mortis is due to a last act of contraction or 

 idio-muscular contraction (Schiff). But its cause is not yet thoroughly 

 understood. When fully established, it is an absolute sign of death. 



In the case of the heart, the rigor mortis produces an excessive con- 

 traction of that organ. The occurrence of this phenomenon in invol- 

 untary muscle, is shown by the rising of water in a glass tube fitted 



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