CHAPTER IV 



THE LOGIC OF EVOLUTION ^ 



OUR sketch of the stages of human evo- 

 lution has given us glimpses of a great 

 drama like one of Wagner's trilogies. 

 Scenes shift and different heroes follow one an- 

 other on the stage. But the story seems discon- 

 nected. The gaps and breaks are very wide. 



This is necessarily the case when we attempt 

 to give in a few pages the history of the animal 

 kingdom in all ages. Even if we had unlimited 

 time and patience for our study, the history 

 would remain incomplete. Our knowledge is 

 very limited. But small and incomplete as it is, 

 it may be valid so far as it goes. I see a great 

 mountain. I have looked at only one side of it, 

 perhaps. I may have correct views concerning 

 that side, even though my knowledge of the 

 whole mountain is very inadequate. 



^ See Appendix Charts V. and VI. 



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