THE NEW EVOLUTION 



parasitic wasps and fungus beetles are scarcely more 

 than one one-hundredth of an inch in length, and 

 some of the wasps are wingless. If these were forced 

 to depend on their own ability to travel they would 

 be placed under an insuperable handicap, for what is 

 a single mile for us is the equivalent of six million 

 miles for them. We, however, have to walk that 

 mile while for them the wind performs the labor. 



Very many living creatures have discovered that 

 the air is sufficiently dense to enable them to use it 

 to support their bodies in passing rapidly from place 

 to place. In other words, they have learned to fly. 

 This is the case with all of the bats, most of the birds, 

 and most of the insects in the adult stage. 



Many creatures, although they do not actually fly 

 like the birds and bats, have their body surface in- 

 creased by expansions of various kinds whereby they 

 are enabled to glide diagonally downward through 

 the air from one place to another. We see this 

 especially in the flying-squirrels, and in the flying 

 lemur (Galeopithecus) and the flying lizards of the 

 oriental regions. 



Still other creatures have various adaptations 

 which, by acting on the air, serve to protect them in 

 one way or another. Thus a cobra when it strikes 

 rises on the extreme end of its body and falls forward; 

 as it falls the expanded hood acts as an air-brake and 

 lessens the shock of its contact with the ground. 

 Tree-living squirrels have long and bushy tails. They 

 can fall from almost any height without danger to 

 themselves. If they fall out of a tree they keep their 



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