146 What Animals Attained 



Animals which struggle may look down with more or less con- 

 tempt on those which are able, by lurking in the crevices or the slack 

 waters of evolutionary currents, to find soft berths where they may 

 exist without a struggle. Such degenerates pay the penalty exacted 

 by the Gods of Biology. When they cease to struggle, they lose 

 their abilities — they not only retrogress in power, but also lose ap- 

 preciation. Every barnacle starts in life as a free-swimming nauplius 

 with eyes and other sense organs. Barnacles which settle on rocks 

 along shore to enjoy life, where waves and tide perennially insure 

 food and certain favorable conditions of life, lose their eyes, and 

 thus to some degree their power to appreciate things outside them- 

 selves. Barnacles which go farther down the road which leads from 

 struggle likewise start in life as apperceptive nauplei; but they attach 

 themselves, not to sturdy rocks, but to other animals and lose all 

 semblance to struggling crustaceans. As adults, they are rotund 

 masses without legs or sense organs. They send root-like absorptive 

 organs into their unlucky hosts and thus steal food; their bodies 

 become soft sacs which produce myriads of eggs. They have a cer- 

 tain success — they continue to live, but they are degraded, spe- 

 cialized, and limited. Land animals because they live in a changeful 

 environment are stimulated to be alert strugglers. 



If it is desirable to move speedily and handle problems encoun- 

 tered in environment with increasing understanding and efficiency, 

 to be progressive, then the struggle to land has been worth while. 

 Speed is a primary quality of land animals (Jehu, 1923). They 

 live in a rarer medium than aquatic animals, and in the atmosphere 

 an abundance of oxygen for metabolic activity permits them to live 

 faster (Krogh, 1916). Fast living requires a continual supply of 

 nutritious food, which is available in land plants, and for terrestrial 

 animals this is supplemented by a greater quantity of radiant energy 

 than is to be had in aquatic habitats. Kennedy (1928) has pointed 

 out that insects are generally distributed in relation to available 

 energy according to their degree of specialization. The primitive 



