AND ITS INHABITANTS 81 



periods" are upon the world, the face of the earth is scenically 

 grand and beautiful and at the same time the struggle for 

 existence among the living is most intense. The rulers of 

 the various domains find themselves overtrained and over- 

 specialized, and succumb one after another to the changing 

 environment. Their places are taken by the small, less 

 specialized, and heretofore little known stocks, which quickly 

 adapt themselves to their environments and become the 

 dominators of the organisms about them. In all of this un- 

 ceasing organic struggle most of the unadaptive families fail 

 to continue; others are pushed by the pulse of life into the 

 less desirable places, where they continue to exist as the static 

 forms the living fossils that tell us so much that is most 

 interesting of once prominent stocks of plants and animals; 

 but at all times much of life quickly responds to the changing 

 environment and is remolded into the more fit, active, and 

 alert types. The experiences thus gained are passed on to 

 successive generations, and so the organic world as a whole 

 advances to ever better living mechanisms endowed with higher 

 and higher mentality. 



The greatest mentality in the sea has been repeatedly de- 

 rived from the continents, first in the fishes, then in the reptiles, 

 and lastly in the mammals, and they have adapted themselves 

 to the sea because of the ease with which they can there prey 

 upon the less alert and intelligent. Such adapted stocks in the 

 course of geologic time grow larger and larger, as, for 

 instance, the whales of today. Out of them, however, comes 

 no higher mentality. They represent an adaptation in the 

 wrong direction, that is, to an easier life, for the highest 

 organisms with the greatest mentality have been developed 

 only on the land where the struggle for existence is fiercest 

 because of the constant necessity of adaptation to an environ- 

 ment subject to intense changes. Organic supremacy is at- 

 tained only through constant vigilance. 



