48 BIOLOGY OF DEATH 



piratory center of the medulla, or that certain tissues consume or destroy 

 substances which are needed for the life of some vital organ. The mischief 

 of death of complex organisms may then be traced to the activity of a 

 black sheep in the society of tissues and organs which constitute a com- 

 plicated multicellular organism." 



At this point I shall not stay to discuss critically each 

 of the hypotheses so summarily reviewed. Instead, I 

 shall make bold to state somewhat categorically my own 

 views on the origin and meaning of death and the deter- 

 mination of longevity ; and in what follows, shall endeavor 

 to set forth in orderly array the evidence which seems to 

 me to support these views. In this process, the relations 

 of what I shall suggest to the conclusions of earlier inves- 

 tigators will, I think, suflSciently appear. 



Let us consider, then, the following picture of life 

 and death: 



1. Life itself is inherently continuous. 



2. Living things, whether single-celled or many- 

 celled organisms, are essentially only physico-chemical 

 machines of extraordinary complexity; but regardless of 

 their degree of complexity only amenable to, and 

 activated in accordance with, physical and chemical law? 

 and principles. 



3. The discontinuity of death is not a necessary or 

 inherent adjunct or consequence of life, but is a rela- 

 tively new phenomenon, which appeared only when and 

 because differentiation of structure and function appeared 

 in the course of evolution. 



4. Death necessarily occurs only in such somata of 

 multicellular organisms as have lost, through differentia- 

 tion and specialization of function, the power of repro- 

 ducing each part if it, for any accidental reason breaks 

 down or is injured ; or still possessing such power in their 

 cells, have lost the necessary mechanism for separating a 



