IO6 THE MEANING OF EVOLUTION 



less likely to be represented in the following genera- 

 tion. The constant result of errors along this line 

 would be to destroy the slow and preserve the swift, 

 and in the course of time it is quite thinkable that 

 only the swift should remain. As the movements 

 grew more and more keen, even the slower of these 

 would pass out, thus tending always to produce the 

 succeeding generation from those who were most 

 rapid, and hence most likely to transfer to their chil- 

 dren a similar power. 



But there is another tendency of animals which 

 leads them when frightened by their enemies to re- 

 main quiet. If this impulse is obeyed thoroughly 

 enough, it is easy to see how the owner of this habit 

 might entirely escape detection by his enemy. Any 

 restless animal unable to restrain his nervous agita- 

 tion naturally betrays his presence and is picked off. 

 The result of evolution along this line would be the 

 exact reverse of the preceding. Those that lay most 

 absolutely quiet would be the parents of succeeding 

 generations, while those who were slow in coming 

 to rest, or were indifferent about remaining quiet, 

 were picked off, and their tendency eliminated from 

 the future of the species. In this way many animals 

 have come to keep entirely quiet in the presence of 

 danger. It is not a sign of high intelligence. As a 

 matter of fact, it is rather a stupid procedure, so far 



