MUSCLE 675 



When muscle is at once raised to a temperature of 75 to 100 C., 

 and all the proteins thus coagulated by heat, there is also an 

 increase in the discharge of carbon dioxide (Fletcher), and the 

 reaction becomes distinctly acid to blue litmus, although still 

 alkaline to red. This is the easiest way of obtaining a maximum 

 evolution of carbon dioxide from an excised muscle. It is 

 highly improbable that a marked production of carbon dioxide 

 should take place in heat -coagulated proteins. We must there- 

 fore suppose that the characteristic decomposition associated 

 with rigor mortis can complete itself in the brief space that 

 elapses between the application of the heat and the heat-coagula- 

 tion of the proteins. This decomposition is wanting in the 

 so-called rigor caused by water, which is not a true rigor, and 

 causes no increase in the carbon dioxide given off. Chloroform, 

 on the other hand, produces a marked increase in the carbon 

 dioxide production, and this is evidently related to its action 

 in hastening the onset of rigor. The process is to some extent 

 influenced by the nervous system, for section of its nerves 

 retards the onset of rigor in the muscles of a limb. This and 

 other facts have given rise to the idea that the rigor is initiated 

 by something analogous to a muscular spasm. Ante-mortem 

 stimulation of the peripheral ends of the vagi, even with currents 

 too weak to cause a perceptible effect upon the heart-beats, pro- 

 longs the period of spontaneous contraction and the irritability 

 of the ventricles after death, and retards the onset of rigor (Joseph 

 and Meltzer). Cold rigor is obtained when frog's muscles are 

 cooled to 15 C. "The muscles remain perfectly translucent. 

 They do not recover their irritability on thawing, but if cooled 

 only to 7 C. they recover (Folin). 



In a human body rigor generally appears not earlier than an 

 hour, and not later than four or five hours, after death. In 

 exceptional cases, however, it may come on at once, and the 

 annals of war and crime contain instances where a man has been 

 found after death still holding with a firm grip the weapon with 

 which he had fought, or which had been thrust into his hand 

 by his murderer. It is related that after one of the battles of 

 the American Revolutionary War some of the dead were found 

 with one eye open and the other closed as in the act of taking 

 aim. A high temperature favours a rapid onset ; a body wrapped 

 up in bed will, other things being equal, become rigid sooner 

 than a body lying stripped in a field. Muscular exhaustion, 

 as we have said, is another favouring condition : hunted animals 

 and the victims of wasting diseases go quickly into rigor. It 

 is a rule, but not an invariable one, that rigor, when it comes on 

 quickly, is short, and lasts longer when it comes on late. All t he 

 muscles of the body do not stiffen at the same time ; the order 



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