RIGOR MORTIS. 9 



The rigidity of muscles after death. Much has been written of late on 

 the subject of the post-mortem rigidity of muscles, though in addition to 

 what was stated by Professor Miiller,* few new facts of importance have 

 been obtained, beyond some which tend to confirm the general opinion, 

 that the rigidity is dependent upon an actual contraction of the mus- 

 cular tissue,f an d that it does not occur until the muscles have lost 

 their irritability, or their power of contracting on the application of 

 ordinary stimuli. Among other facts in proof of the latter of these 

 circumstances, it has been observed by Dr. Gierlichs,J that in frogs, in 

 whom, as in other reptiles, the muscular irritability is very persistent, the 

 rigor mortis is often not established for three or four days after death ; 

 that in birds, on the other hand, whose muscular irritability endures but a 

 short time after death, the post-mortem rigidity ensues quickly. Addi- 

 tional proof also has been procured, both by Dr. Gierlichs and other 

 observers, that all circumstances which cause a speedy exhaustion of 

 muscular irritability, induce an early occurrence of the cadaveric rigidity, 

 while conditions by which the disappearance of the irritability is delayed, 

 are succeeded by a tardy onset of this rigidity. 



The rigidity of voluntary muscles, from being the most evident, has 

 attracted most attention, and the phenomenon has, until lately, been 

 described solely in relation to this class of muscles, but sufficient evidence 

 has now been accumulated to warrant the conclusion, that the involuntary 

 muscles also are affected by a post-mortem rigidity, which is, in all essen- 

 tial respects, comparable with that seated in the voluntary muscles. And 

 this is true, not merely with regard to those involuntary muscles which, 

 such as the blood and lymphatic hearts, are constructed of striped fibres, 

 but also with regard to the tissues composed of unstriped fibres, such as the 

 muscular coat of the intestines, and the contractile coat of blood-vessels and 

 of the large excretory ducts. The observations of Dr. George Budd and of 

 Mr. Paget,|| have proved this in the case of the heart; and the occurrence 

 of the rigidity in the digestive canal has been shewn by Valentin,^" who 

 found that if a graduated tube be connected with a portion of intestine 

 taken from a recently slain animal, 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. The contrac- 

 tion of the blood-vessels after death was observed by John Hunter, and is 

 now regarded as a well established fact, and one by which the empty state 

 of the arterial system after death is in great measure explained. 



* Physiology, p. 890, et seq. 



t See especially Mr. Bowman in the Philosophical Transactions, 1840 ; and M. Bruch in 

 Gazette Medicale de Paris, Novembre 1, 1845. 



t Schmidt's Jahrbuch. Mai, 1844. Medico-Chirurg. Trans, vol. xxi. p. 296. 



II Report on the Progress of Anat. Physiol. 1842-3, p. 6. 

 1 Physiologic, b. ii. p. 36. 



