A VIEW IN PERSPECTIVE. 147 



themselves together into colonies, and then devel- 

 oped a most complicated set of instincts, mostly 

 adapted for the preservation and integrity of the 

 colony. Now while instinct is indeed a mental 

 factor quite distinct from intelligence, it is, like in- 

 telligence, a function of the nervous system. The 

 insects thus first inaugurated the development of 

 the nervous system to an extent which made its 

 powers prominent factors in the preservation of the 

 race. At what geological date instinct became such 

 a prominent factor in the life of insects we cannot 

 say. The individuals found in the Cretaceous (8) 

 were all sexual individuals. Now the formation 

 of colonies is usually accompanied by the produc- 

 tion of sexless individuals (neuters, workers). It 

 would therefore seem that the insects of the Creta- 

 ceous had not yet acquired their social habits, and 

 that the high development of instinct was subsequent 

 to this period. At all events it was a late event in 

 the history of insects, just as the development of 

 intelligence was a late event in the life of verte- 

 brates, and it seems probable that instinct reached a 

 high development in the Tertiary (9) before the 

 special development of intelligence began. 



Intelligence. 



We are now prepared to recognize a period in 

 the history of animals when intelligence had be- 

 come the predominant feature of nature. This of 

 course brings us to man, and we are now in posi- 

 tion to consider the important question of the 

 relation of man to this history of life. For our pur- 



