466 MOTION. 



the bodies of persons exhausted by chronic diseases ; and its 

 tardy onset and long continuance after sudden death from 

 acute diseases. In some cases of sudden death from lightning, 

 violent injuries, or paroxysms of passion, rigor mortis has been 

 said not to occur at all ; but this is not always the case. It 

 may, indeed, be doubted whether there is really a complete 

 absence of the post-mortem rigidity in any such cases ; for the 

 experiments of M. Brown-Sequard with electro-magnetism 

 make it probable that the rigidity may supervene immediately 

 after death, and then pass away with such rapidity as to be 

 scarcely observable. Thus, he took five rabbits, and killed 

 them by removing their hearts. In the first, rigidity came on 

 in ten hours, and lasted 192 hours ; in the second, which was 

 feebly electrified, it commenced in seven hours, and lasted 144; 

 in the third, which was more strongly electrified, it came on 

 in two, and lasted 72 hours ; in the fourth, which was still 

 more strongly electrified, it came on in one hour, and lasted 20 ; 

 while, in the last rabbit, which was submitted to a powerful 

 electro-galvanic current, the rigidity ensued in seven minutes 

 after death, and passed away in 25 minutes. From this it 

 appears that the more powerful the electric current, the sooner 

 does the rigidity ensue, and the shorter is its duration ; and as 

 the lightning shock is so much more powerful than any ordi- 

 nary electric discharge, the rigidity may ensue so early after 

 death and pass away so rapidly as to escape detection. The 

 influence exercised upon the onset and duration of post-mortem 

 rigidity by causes which exhaust the irritability of the mus- 

 cles, was well illustrated in further experiments by the same 

 physiologist, in which he found that the rigor mortis ensued 

 far more rapidly and lasted for a shorter period in those mus- 

 cles which had been powerfully electrified just before death 

 than in those which had not been thus acted upon. 



The occurrence of rigor mortis is not prevented by the pre- 

 vious existence of paralysis in a part, provided the paralysis 

 has not been attended with very imperfect nutrition of the 

 muscular tissue. 



The rigidity affects the involuntary as well as the voluntary 

 muscles, whether they be constructed of striped or unstriped 

 fibres. The rigidity of involuntary muscles with striped fibres 

 is shown in the contraction of the heart after death. The con- 

 traction of the muscles with unstriped fibres is shown by an 

 experiment of Valentin, who found that if a graduated tube 

 connected with a portion of intestine taken from a recently- 

 slain animal, be filled with water, and tied at the opposite 

 end, the water will in a few hours rise to a considerable height 

 in the tube, owing to the contraction of the intestinal walls. 



