CHAPTER IV 



THE DIMENSION OF LIFE OR THE PLACE OF LIFE IN 



NATURE 



WE have now our tools for locating in part biological 

 phenomena among the other phenomena of nature ; we 

 know that they have a place between the phenomena of 

 equilibrium peculiar to colloids and the chemical phenomena 

 of molecular equilibrium. Moreover, we shall be led to a 

 more exact localization when we find what physical agents 

 are capable of influencing living substances. For example, 

 it interests us to know within what limits of vibratory 

 velocity sound movements are capable of influencing proto- 

 plasms, and within what limits of wave-length certain 

 vibrations analogous to light vibrations can modify the 

 chemical substances which constitute protoplasm. 

 f % ;We do not yet know the essential biological phenomenon, 

 but we can foresee its dimension. 



There are chemical reactions outside of life ; there are 

 colloid bodies which are not living ; therefore none of the 

 characters so far considered will allow us to define life with 

 relation to not-living substances. We only know that 

 every living substance is in the colloid state and is the seat 

 of chemical reactions, and that there is a relation of cause 

 and effect between its colloidal equilibrium and its chemical 

 activity and this is a great deal. 



There are measurable quantities besides those which 

 come back to measures of length. Temperature, for example, 



