56 THE NATURE AND ORIGIN OF LIFE 



such language, by the very fact that it applies to a thousand 

 not-living phenomena, is not the language best adapted to 

 the description of vital phenomena. In the case of alcohols 

 we can also describe everything in the general language 

 of chemistry ; but if we wish a concise study of alcohols 

 taken by themselves, we use the language of the function 

 alcohol, which applies to alcohols alone. In the same way, 

 the fourth part of this book will give us a language of 

 functions a truly biological language which will enable 

 us to reduce to a few words the general expression of all 

 vital phenomena. 



The approximate law of assimilation, by setting life in 

 its place among other natural phenomena, satisfies us at 

 first ; but we have to acknowledge in many cases that its 

 definition is very platonic. It enables us to recognize life 

 in beings by means of long-continued observation, but even 

 then only during the period of growth. In the adult state 

 or in the period of decrepitude the phenomenon of assimi- 

 lation, though we cannot doubt that it is still very real, is 

 hidden by antagonistic phenomena. 



If I see a cat, motionless and eyes ablaze, watching a 

 sparrow, I know very well that it is alive ; I recognize 

 it by certain signs which do not deceive. And yet I have 

 no means of assuring myself that phenomena of assimila- 

 tion are going on in the cat's interior. The approximate 

 law of assimilation helps me to know only the results of such 

 phenomena taken as a whole ; but they are accompanied 

 by manifestations, at sight of which I recognize life without 

 being able to define them exactly. It is also true that I 

 may be deceived in my observation ; a very clever taxi- 

 dermist may have given the illusion of life by properly 

 arranging the dead bodies of a cat and a sparrow. Possibly 

 science may some day bestow on us an apparatus enabling 



