CHAPTER VIII 



NATURAL DEATH, PUBLIC HEALTH, AND THE 



POPULATION PEOBLEM. 



SUMMAKY OF KESULTS 



I have attempted to review some of the important 

 biological and statistical contributions which have been 

 made to the knowledge of natural death and the duration 

 of life, and to synthesize these scattered results into 

 a coherent unified whole. In the present chapter I shall 

 endeavor to summarize, in the briefest way, the scattered 

 facts which have been passed in review, and to follow a 

 presentation of the general results to which they lead 

 with some discussion of what we may reasonably regard 

 the future as having in store for us, so far as may be 

 judged from our present knowledge of the trend of events. 



What are the general results of our review of the gen- 

 eral biology of death? In the first place, one perceives that 

 natural death is a relatively new thing, which appeared 

 first in evolution when differentiation of cells for partic- 

 ular functions came into existence. Unicellular ani- 

 mals are, and always have been, immortal. The cells of 

 higher organisms, set apart for reproduction in the 

 course of differentiation during evolution, are Immortal. 

 The only requisite conditions to make their potential im- 

 mortality actual are physico-chemical in nature and are 

 now fairly well understood, particularly as a result of 

 the investigations of Loeb upon artificial parthenogenesis 

 and related phenomena, The essential and important 



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