144: SPECIAL PHYSIOLOGY. 



the passive, condition of the muscular fibre, and this is probably still 

 the prevailing belief. But Dr. Radcliffe has advanced the opinion, 

 from a study of the electrical relations of nerve and muscle, that the 

 state of elongation should be regarded as the active condition of this 

 tissue, and that of contraction as the passive condition, or state of rest. 

 By an inversion of the ordinary terms of description all the phenom- 

 ena can thus be equally well explained, but the doctrine itself is not 

 yet established. It seems natural to suppose, from our knowledge of 

 the polar electrical condition of living muscles, and of the disturbance 

 of its electrical state during contraction, that the dark sarcous ele- 

 ments or disdiaclasts, and the light intervening elements, may be in 

 opposite polar electrical states ; and that accordingly molecular at- 

 tractions and repulsions may, under excitation, occur, as the immedi- 

 ate causes of motion between them ; but this is quite conjectural. It 

 has been offered as a mere suggestion, to be hereafter again alluded 

 to, that osmotic changes in the contents of the tubular sarcolemma of 

 the muscular fibre, may possibly occur as essential conditions of its 

 alternate contractions and relaxations (Graham). 



The Rigidity of Death, or Rigor Mortis. 



Within a certain period after death, the muscles of the body, the 

 muscular substance of the heart, and also the parts composed of the 

 non-striated muscular fibres, undergo, after losing their irritability, a 

 general stiffening, which is called the rigor mortis, or cadaveric rigid- 

 ity, or the rigidity of death. This rigidity in the muscles is so perfect 

 that the joints become fixed, usually in the position in which the body 

 lies at the moment of death ; but, in certain cases, the occurrence of 

 the rigor mortis is accompanied by displacements of the limbs, even to 

 the raising up the corpse into a sitting posture. Usually the more 

 powerful muscles give, in dying, and in assuming their rigid condition 

 afterwards, certain definite positions to particular parts of the body ; 

 thus, the upper eyelid is drawn slightly upwards, the lower jaw is 

 closed against the upper one (whereas at the moment of death it falls 

 by relaxation of its muscles), the fore-arm is slightly flexed, the fin- 

 gers are bent, and the thumb turned inwards on the palm ; whilst the 

 leg and foot are everted and extended, the flexors of the upper limb 

 and the extensors of the lower limb being stronger than their antago- 

 nists. These movements must be distinguished from those which have 

 been observed, soon after death, in cases of cholera and yellow fever, 

 and which are attributed to an unusual persistence of the proper mus- 

 cular contractility. 



The rigor mortis may begin within ten minutes of death, but it 

 usually comes on between seven and eighteen hours, sometimes as late 

 as thirty-six hours. Its usual duration is from twenty-four to thirty- 

 six hours, but it may pass off much more quickly, or last for several, 

 as many as six, days. It disappears at the commencement of putre- 

 faction. The sooner it comes on the shorter its duration, and when it 

 comes on late it continues longer. It appears latest, is most intense, 

 and lasts longest, in persons dying rapidly in a state of health. In 



