452 OF MUSCULAR CONTRACTILITY. 



cord. This contraction, which is obviously of a tetanic character, ceases after a few hours, 

 and is then succeeded by a state of flexibility, after which the ordinary rigidity supervenes. 

 The following case illustrates the nature of the inquiries, to which this 'condition may give 

 rise.* The body of a man was found in a ditch, with the trunk and limbs in such a relative 

 position, as could only be maintained by the stiffness of the articulations. This stiffness must 

 have come on at the very moment when the body took that position; unless it could be 

 imagined that the body had been supported by the alleged murderers, until the joints were 

 locked by cadaveric stiffness. A post-mortem examination showed, that there was no neces- 

 sity for this supposition, obviously a very improbable one in itself; by affording sufficient 

 evidence, that apoplexy, resulting from chronic disease, was the cause of death. A case 

 occurred a few years since in Scotland, in which the same plea was raised. The body was 

 found in a position in which it could have only been retained by rigidity of the joints ; and 

 it was pleaded on the part of the prisoner, that death had been natural, and had resulted 

 from fracture of the processus dentatus, causing sudden pressure upon the spinal cord, whence 

 the spasmodic rigidity would naturally result. Proof was deficient, however, as 'to the 

 existence of this lesion before death ; and the position of the body rather resembled that into 

 which it might have been forced during the rigidity, than that in which it would probably 

 have been at the moment of death. There were also marks of violence, and many other 

 suspicious circumstances; but the prisoner was acquitted, chiefly from want of evidence 

 against him. What seemed to indicate that the rigidity was of the ordinary cadaveric nature, 

 Avas, that there was no evidence of the body having become flexible and again stiffened ; as 

 it would probably have done, had the rigidity been of the spasmodic character. 



597. As the property of Tonicity manifests itself most decidedly in the non- 

 striated muscles in the living body, so do we find this post-mortem contraction 

 most remarkable in them. As soon as the muscular walls of the several cavi- 

 ties lose their irritability, they begin to contract firmly upon their contents, 

 and thus become stiff and firm, though they were previously flaccid. In this 

 manner the ventricles of the heart, which are the first parts to lose their 

 irritability, become rigid and contracted within an hour or two after death ; 

 and usually remain in that state for ten or twelve hours, sometimes for 

 twenty-four or thirty-six, then again becoming relaxed and flaccid. This 

 rigid contracted state of the heart, in which the walls are thickened and the 

 cavities diminished, was formerly supposed to be a result of disease, and 

 was termed concentric hypertrophy; but it is now known, from the inquiries 

 of Mr. Paget, to be the natural condition of the organ, at the period when the 

 rigor mortis occurs in it. The contraction of the arterial tubes is so great, as 

 to produce for the time a great diminution in their calibre ; and this doubtless 

 contributes to the passage of the blood from the arterial into the venous sys- 

 tem, which almost invariably takes place within a few hours after death. The 

 arteries then enlarge again, and become quite flaccid, their tubes being emptied 

 of their previous contents ; and it was from this circumstance, that the ancient 

 Physiologists were led to imagine, that the arteries are not destined to carry 

 blood, but air. 



4. Energy and Rapidity of Muscular Contraction. 



598. The energy of Muscular contraction is of course to be most remarkably 

 observed in those instances in which the continual exercise of particular parts 

 has occasioned an increased determination of blood towards them, and in con- 

 sequence a permanent augmentation in their bulk. This has been the case, 

 for example, with persons who have gained their livelihood by exhibiting 

 feats of strength. Much will, of course, depend on the mechanically-advantage- 

 ous application of muscular power ; and in this manner, effects may be pro- 

 duced, even by persons of ordinary strength, which would not have been 

 thought credible. In lifting a heavy weight in each hand, for example, a per- 

 son who keeps his back perfectly rigid, so as to throw the pressure vertically 

 upon the pelvis, and only uses thw powerful extensors of the thigh and calf, 

 by straightening the knees (previously somewhat flexed), and bringing the leg 

 to a right angle with the foot, will have a great advantage over one who uses 



* Annalcs d'Hygiene, torn. vii. 



