142 THE NATURE AND ORIGIN OF LIFE 



contradiction with the new law of the Conservation of 

 Energy. An incomplete observation of living bodies started 

 up in our ancestors' brains a problem of perpetual move- 

 ment a problem, the vanity of which has been demonstrated 

 by modern science. It consisted in finding some means of 

 making an isolated system produce continuous mechanical 

 work without expending any provision whatever of energy. 



Nowadays the theorem, Nihil ex nihilo (nothing is made 

 of nothing) is applied to biological facts just as much as to 

 the facts of mechanics, physics and chemistry. Only 

 we must take care not to consider the living being as forming, 

 in the extent of its body taken alone, a complete system of 

 energy. 



Every instant, it is true, the individual body occupies a 

 limited extent of space and is capable of circumscription 

 as a whole ; but we know that this body A has not within 

 itself all the elements of its activity. The working of the 

 animal as a whole at a given moment must, on the contrary, 

 as we have already seen, be represented by the symbolic 

 formula (A x B) a formula in which the term B represents 

 the sum total of the external conditions intervening to 

 determine the working. It is only in this whole (A x B) 

 that we can verify the law of the Conservation of Energy. 



Every instant the animal receives from without light, 

 heat, and other radiations and chemical substances like 

 oxygen, and gives out to its environment radiations (radiant 

 heat) and chemical substances (water-vapour, carbonic 

 acid). From this enumeration, as taking place only inter- 

 mittently in the higher animals, we omit food exchanges 

 which are the most important of all (absorption of 

 food, excrementation). There are also sound vibrations, 

 olfactory impressions, etc. No animal exists without its 

 environment. 



