LAND LIFE BEGINS 47 



river's edge, you will understand this. The roots form 

 a dense thicket, into which the giant salamander or 

 large fish could not follow the little amphibian. But 

 legs are useless in such a world. A strong wriggling 

 body is needed; and the fossil skeletons we have 

 show us that this branch of the amphibians slowly 

 changed until they must have looked externally like 

 water snakes. 



These illustrations of the machinery of evolution 

 during the long forest period will suffice. It seems 

 to have lasted about a million and a half years; or 

 the whole period we have just surveyed may have 

 lasted ten million years. In spite of all the changes 

 we have noticed, it was a period of slow evolution. 

 Life is never quite stagnant, unless some race of 

 living things is removed entirely from competition 

 with others and has easy conditions. I mean that 

 for a living family of low intelligence, which depends 

 on almost mechanical stimulation from its surround- 

 ings, such conditions generally mean stagnation. 

 They are rarely found, however, and we saw that 

 there was a brisk struggle in the coal forests. Yet, 

 when we think of the enormous period occupied 

 by these developments, the pace of life was slow. 

 Fat salamanders, fat insects, fat spiders, and so on, 

 lived out the warm days sluggishly and contentedly. 

 Now a fearful "revolution" is at hand, and new 

 dynasties are to come to the throne. 



