74 WHAT EVOLUTION IS 



other form would arise and evolution 

 could be said to have taken place. 



Lamarck conceived the effect of en- 

 vironmental change on animals to be 

 carried out in a rather more complex 

 way than on plants. He illustrated 

 this by several examples such as the 

 webbed foot of water birds and the 

 long neck of the giraffe. 



Lamarck rightly believed that land 

 birds were the ancestors of water 

 birds, and in thinking of the transi- 

 tion, he pictured land birds coming 

 more and more to frequent the shore, 

 to pass much of their time in shallow 

 water and to seek their food there. 

 Such newcomers would from time to 

 time get into deep water and naturally 

 attempt to propel themselves by kick- 

 ing with their legs. The muscular 

 exercise of kicking would induce an 

 extra flow of blood to the legs whose 

 bones, muscles, skin, and the like 



