DEATH OF THE MUSCLE. 87 



general death at a period varying from thirty minutes 

 to several hours. 



6. On looking at the dead muscle of a frog it will be 

 noticed that its appearance differs essentially from that 

 of a fresh muscle. It does not appear so transparent, is 

 much duller and whiter in colour ; at the same time it 

 feels harder, less elastic, but is capable of greater ex- 

 tension, and, finally, it is tender and easily torn apart, 

 the more so the further the change has proceeded. Ex- 

 actly similar changes affect the muscles of a dead body. 

 This is called the death-stiffening (rigor mortis). E. du 

 Bois-Reymond showed that on the occurrence of this 

 death-stiffening the original alkaline or neutral reaction 

 gives place to an acid reaction. This is probably due to 

 the transformation of the neutral -glycogen and inosit 

 into lactic acid, which with the alkalis present forms 

 acid-reacting salts. This change is the cause of the 

 fact that butcher's meat, which remains hard and tough 

 if it is cooked directly after death, becomes gradually 

 more tender. If the meat is allowed to lie for a time 

 after death, the death-stiffening again relaxes, the sepa- 

 rate bundles of fibres no longer adhere so firmly to 

 each other ; and when in this condition the meat is 

 better adapted for preparation as food, because it is 

 tender and may be more easily chewed, and because 

 it offers less resistance to the digestive juices. 



The death-stiffening in its chemical nature, there- 

 fore, bears a certain resemblance to the changes which 

 occur during the activity of the muscle. In the latter 

 case also an acid is formed, which is, however, again 

 eliminated and carried away by the blood. In the death- 

 stiffening this elimination cannot occur, the circulation 

 of the blood having ceased. For this reason death- 



