24 MAN AN ADAPTIVE MECHANISM 



and again by flesh-eating animals, which prey upon 

 the herbivora. In their bodies it is reduced again 

 to carbon dioxid and exhaled, only to be reabsorbed 

 again by plants, stored again in plants by sunlight 

 and again taken into the animal body. Thus occurs 

 the ceaseless round of matter and energy, by which 

 is perpetuated a complete cycle of " adaptation," not 

 only of plants and animals to each other, but of ele- 

 ments to organisms, and of all to the sun's radiance. 



As we rise higher in the life scale, the law of " adapta- 

 tion, " by which character is silently and invisibly 

 determined in the world of atoms, becomes more obvious 

 and concrete, until in the world of animals it is exempli- 

 fied by a face-to-face conflict of individuals which is 

 more desperate and thrilling than any artificial drama 

 ever staged by man. Here in a world-wide trail of 

 blood are to be traced the workings of that invisible 

 law of balance, the violation of which among gases 

 meant only " friction." On land and sea, in forest, 

 field and stream, are to be seen evidences of the mighty 

 conflict resulting in the elimination of those individuals 

 unfit for survival, and the perpetuation of species 

 safely modified to their surroundings. In looking out 

 upon tne face of nature, radiant with sunshine, color 

 and the song of birds, it is hard to believe that a whole- 

 sale destruction of life is being enacted in every corner 

 of verdant splendor. Yet each one of those little birds 

 singing so blithely, each of the skipping grasshoppers, 

 has made a meal of some other living thing in its 

 environment. In the downward swoop of the robin 

 upon the worm, in the hasty scamper of a rabbit 

 through the fern, in the steady pecking of the wood- 



