48 THE BEGINNINGS OF LIFE. 



chemical in the ordinary acceptation of the word. What 

 has already been accomplished may well lead us to be- 

 lieve that, as time goes on, the torch of Science will 

 enable us to penetrate still further and to throw light 

 upon some of the remaining mysteries of vital pheno- 

 mena. 



All that we know already, however, concerning the 

 higher animals points strongly to the truth of the con- 

 clusion which is thus expressed by Gavarret : c The 

 action of oxygen upon the material of the blood is then 

 the sole source 1 of force of which the animal can avail 

 itself. In order to accomplish all the internal and ex- 

 ternal work necessary for the nutrition and for the 

 development of the individual, for the propagation of 

 its kind, and for its action upon the surrounding world, 

 the animal, makes use of the force set at liberty during 

 the conflict of oxygen borrowed from the air with the 

 elements of its food. But these alimentary substances 

 in again taking on, under the influence of the burn- 

 ing action of oxygen, their primitive mineral forms, 

 can only set at liberty, and place at the disposal of the 

 animal, their own potential energy that is to say, that 

 quantity of force which was borrowed by the plant 

 from the solar radiations in order to convert mineral 

 matter into organic matter. 5 



Matter and force are inseparable neither can exist 

 alone ; and just as the substances which enter into the 



1 Either immediate, or mediate. 



