212 The Science of Life. 



sions of sexual emotion, "such expression may have 

 suggestive value, and serve to evoke an answering 

 emotion. In this case the act of pairing would be cor- 

 related with the expression of sexual emotion through 

 certain specialized activities; and those individuals 

 which were not expressive, together with those which 

 were insensible to the suggestive influence of expres- 

 sion, would be less ready to mate and to transmit the 

 specialized modes of expression " (Lloyd Morgan). 



(e) Groos has suggested a way of looking at the 

 facts which well deserves consideration. Since the 

 sexual instinct is obviously, in most cases, of extraordi- 

 nary strength, it is in the interest of race-preservation 

 that its satisfaction should be kept within bounds. In 

 relation to this we find that a long-continued prelimin- 

 ary excitement is often necessary. In particular, the 

 instinctive coyness of the female has to be overcome. 

 And it is in reference to this end that the often elaborate 

 courting instincts have been evolved, i.e. in the course 

 of natural rather than sexual selection. 



Chapter XVI. 

 Evolution of Evolution-Theory. 



The Evolution Idea Greek Period Mediaval Period Scientific Renais- 

 sance Philosophic Evolutionists Speculative Evolutionists Pio- 

 neers of Modern Evolution- Doctrine Darwinism Conflict of 

 Opinions Some Recent Steps Conclusion. 



The general idea of organic evolution that the present 

 is the child of the past seems to be almost as old as 

 The Evolution the earliest records of clear thinking. It is 

 idea. i n great part just the idea of history of 



human history projected upon the organic world, but 

 it is differentiated by the qualification that the continu- 

 ous "becoming" had been wrought out by forces in- 

 herent in the organisms themselves and in their environ- 

 ment. In other words, evolution is a natural history. 



