86 THE HUMAN BODY 



in digestion : the myosin is thus rendered soluble in water and un- 

 coagulable by heat, and such extracts if properly prepared are 

 nutritious and can often be absorbed when meat in the solid form 

 cannot be digested : they may thus help the stomach over a crisis, 

 but are not, even the best of them, to be depended on as anything 

 but temporary substitutes for other food ; or in some cases as use- 

 ful additions to it. 



Rigor Mortis. During life and for a certain time after general 

 death the muscles are soft, translucent, extensible and elastic, and 

 neutral or feebly alkaline in reaction; after a period which in warm- 

 blooded animals is brief (varying from a few minutes to three or 

 four hours) they gradually become harder, more opaque, less ex- 

 tensible and less elastic, and distinctly acid in reaction. The 

 result of these changes is the well-known cadaveric rigidity or 

 rigor mortis. It was formerly very generally believed that the 

 cause of rigor is the change of soluble myogen and myosin to in- 

 soluble myogen fibrin and myosin fibrin. Quite recently, how- 

 ever, some physiologists have called attention to the strong 

 probability that death stiffening may be due to the considerable 

 production of sarcolactic acid which is known to accompany the 

 death process. In support of their view may be cited the well- 

 known tendency of animals or men killed suddenly in the midst of 

 violent exertion to stiffen very quickly. Men killed in battle often 

 retain the postures in which death overtook them. Hard muscular 

 work involves a large production of sarcolactic acid, a condition 

 favorable according to the view quoted, to a prompt onset of rigor. 



