GENERAL INTRODUCTION 7 



resistance and longevity, a living cell that cannot die is 

 unthinkable. 



The mere absence of growth and energy formation 

 does not necessarily mean death; the same symptoms 

 are characteristic for dormancy. We can imagine con- 

 ditions where we have neither growth nor fermentation 

 and yet no death. This is probably the case with dry 

 bacteria in a vacuum at very low temperatures. The 

 discussion of the causes of death will show that dying is 

 a chemical process. 



Another function is also found regularly, or at least 

 assumed for all cells, i.e. endogenous catabolism. Catabo- 

 lism is assumed for all cells because all cells die from 

 starvation, death by starvation meaning that a deteriora- 

 tion of some cell compounds occurs which, in normally 

 nourished cells, is counteracted by constructive processes. 



Endogenous catabolism shall mean here the deteriora- 

 tion of cell compounds, but not of the food taken in. 

 This definition may eventually lead to difficulties, for 

 we may assume that the food combines with some cell 

 compounds before being decomposed. But we shall try 

 to avoid hair-splitting as much as possible. 



We have, then, endogenous catabolism, death, energy 

 formation and growth (and, eventually, multiplication) 

 as the four functions which are indispensable for life, 

 the primitive functions of hfe, so to speak. This book 

 is limited entirely to the discussion of these four functions. 



Of these four functions, endogenous catabolism is the 

 least dependent of all. The process of dying may, in 

 some cases, be interlinked with catabolism, as in death 

 by starvation. Growth is the most dependent function, 

 being possible only when energy is furnished, and 

 inseparable from catabolism. It would be impossible to 

 discuss growth without having first studied energy 



