Fitness in the Living World 33 



the admiration of the thoughtful, let the following classi- 

 fication and illustrative examples testify: 



I. RACIAL OR INHERITED ADAPTATIONS 



Inherited adaptations are those which appear in the 

 development of individuals as if in anticipation of future 

 needs and not as a result of present ones. The eye, for 

 example, usually develops in the entire absence of light, and 

 its various parts are formed as if in anticipation of their 

 future uses; the same may be said of almost every other 

 inherited adaptation. Particular adaptations characterize 

 certain races, species and larger groups of organisms. 

 Among these are innumerable structures, functions, habits, 

 and instincts; indeed, one can think of scarcely any normal 

 structure or function, reflex or instinct, that does not illus- 

 trate such racial or inherited adaptation. 



1. The Efficiency of the Living Machine 



This is an age of machinery, and the fitness of any 

 machine is measured by its efficiency. Let us consider the 

 fitness of the living machine as contrasted with those of 

 human invention. 



The frame or skeleton of most vertebrates is so con- 

 structed as to give the maximum of strength with the mini- 

 mum of weight. Long ages before men had thought of 

 using tubular frames in machines such as bicycles, nature 

 had been using them in the shafts of long bones; ages before 

 wire wheels and tangential spokes were thought of spicules 

 and trabeculae of bone were laced through the ends of long 

 bones so as to afford maximum strength with minimum 

 weight. Long before any human being had discovered, used, 

 or classified the different forms of levers, nature had been 

 using them in the limbs of arthropods and vertebrates. 



