CHAPTER XXII 

 DEATH AND THE DURATION OF LIFE 



Nature of Death. — Death is defined as the cessation 

 of life. An organism that for weeks or years has moved, 

 undergone waste, repair, and growth, and has responded 

 to stimuli, finally ceases these activities. It dies, and the 

 protoplasm composing its body never regains its capacity 

 in this respect, but decomposes into simpler, more ele- 

 mental and lifeless compounds. The advent of death is 

 preceded, at least in higher animals, by old age changes 

 in which the operations of the cells gradually slow down. 

 Even when death occurs, its effects are not instantaneous. 

 The nervous system fails in its functions, the heart stops 

 beating, breathing ceases; but the cells of the skin and 

 hair may continue to develop for hours, and the white 

 corpuscles exhibit their characteristic movements. 

 Among many of the lower animals these differences in 

 cell vitality are even more marked, several functions 

 of the body continuing for a considerable period even 

 though the head be severed. A number of animals, such 

 as the opossum and certain insects, may feign death, and 

 the cases of so-called suspended animation, in which a 

 human being, for example, sinks into a torpid condition, 

 are often such perfect counterfeits of death that the 

 closest scrutiny is necessary to detect the difference. 



Hibernation or Winter Sleep. — A type of par- 

 tially suspended animation, death-like in its general 

 features and known as hibernation or winter sleep, 

 normally occurs in numerous animals during the cold 

 season when food is scarce. In the fall several species 

 of bears, hedgehogs, prairie dogs, squirrels, bats, and other 



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