EVOLUTION THE KEY TO NATURE 9 



evolution recognized makes him immortal in science. 

 His theory is, as a matter of fact, very much disputed. 

 Darwin looked about him, and saw that far more 

 living things are born than nature can sustain or the 

 earth hold . He saw that this caused a great ' ' struggle 

 for life," and that the ''fittest" — those best equipped 

 to meet their particular struggle — survived. Nature, 

 in other words, ** selected" the fittest; and so his 

 theory is called "natural selection." Take the hawk. 

 Its success in life depends on keenness of eye and 

 strength of wing. Every time a few hawks are 

 hatched some will have slightly better eyes or wings 

 than others. They have more chance of surviving; 

 and they will hand on their improved eyes and wings 

 to the next generation. In the course of hundreds of 

 thousands of years these minute improvements at 

 each birth will have brought about a much higher 

 type of bird. "Natural selection," he said, was the 

 agency of evolution. 



That this process does actually go on throughout 

 nature, and even in our social and economic order, 

 any person can see ; but it is now disputed if it is the 

 general machinery of evolution. The pioneer in any 

 new field of research generally makes some mistakes. 

 Some now think that the embryological machinery, 

 not the destructive or "selective" work of nature, is 

 the great agency. Some think that the gradual 

 strengthening during a long period of small improve- 

 ments in each generation is not a satisfactory explana- 



