102 THE BEGINNINGS OF LIFE. 



intensity. And here indeed, remembering the relations 

 between the atomic weights in the two cases, may we 

 not suspect a close analogy between the de-oxidation of 

 a metallic oxide by carbon under the influence of the 

 longer ethereal waves, and the decarbonization of car- 

 bonic acid l by hydrogen under the influence of the 

 shorter ethereal waves ? ' 



These discoveries and suggestions are, we think, of 

 the deepest interest and importance. They open up 

 possibilities of explaining problems which had hitherto 

 seemed well-nigh insoluble, and that, too, in the sim- 

 plest way, and by the application of strictly physical 

 principles. Having to deal with such mutable ma- 

 terials as the unstable and big-atomed colloids, and 

 being aware of the above-mentioned explanations as 

 to the way in which vibrations communicated to an 

 imponderable ether may bring about motions amongst 

 the atoms of ponderable matter, much of the seem- 

 ingly impenetrable mystery which has hitherto en- 

 shrouded the nature of the changes taking place in 

 living tissues, appears to be notably lessened. No 

 subject seemed more hopelessly difficult, and yet we 

 can now only agree with Mr. Spencer when he 

 says: c These conceptions help us to some dim no- 

 tion of the mode in which changes are wrought by 



The decomposition of carbonic acid and the fixation of carbon as 

 one of the component elements of living tissue is continually taking 

 place in the leaves of plants under the stimulus of solar light and 

 its actinic rays. 



