332 The Vital Phenomenon: Assimilation 



as we have affirmed before, can help to explain in great 

 part the essential character of the vital phenomenon itself 

 in all its generality that is assimilation. 



The fact that strikes us first of all is, that the vital 

 phenomenon depends upon continual reproduction, for 

 assimilation constantly reproduces the substance which is 

 gradually consumed. It is to be expected therefore, that 

 if there are any fundamental properties of living organic 

 substance which explain the phenomena of development 

 or of reproduction in general, they must then be capable 

 of accounting for assimilation also, inasmuch as it is 

 itself a phenomenon of reproduction. 



That being granted it will be worth while that we 

 next stop for an instant to take a look at and consider 

 briefly a few of the principal conceptions which biologists 

 have put forward on the nature of either the vital phe- 

 nomen or of assimilation, and which are of the greatest 

 interest from our point of view. 



Roux, for example, rightly urges that the nature of 

 life must be dynamic. "Life is in its essence a process, 

 and cannot therefore have a static definition. It is 

 therefore only a processive and consequently functional 

 definition which can approximate the essence of organic 

 life." 249 



On the other side we have already seen the reasons 

 for concluding that the essence of the vital phenomenon 

 consists in an activation of nervous energy. We re- 

 call that according to Orr for example, the funda- 

 mental property of living substance is an "elemental 

 nervousness." 25 



248 Roux : tlber die Bedeutung der Kernteilungsfiguren. Leipzig, 

 Engelmann, 1883. P. 18. Gesamm. Abhandl. Bd. II. P. 142. 

 260 Orr : A Theory of Development and Heredity P. 86. 



