144 THE HAUNTS OF LIFE 



form within the egg. For every animal in its 

 early life tends in a greater or less degree to 

 repeat in its personal history some of the stages 

 that have been gone through in the history of 

 its race, and much of this can be made out by 

 a careful study of the stages that appear, often 

 to disappear again very quickly, in the earlier 

 period of the building up of the body of the 

 individual. 



The same thing is true to some extent of 

 habits, and, in particular, many animals have 

 an impulse to go back at the breeding-season 

 to bring forth their young in the place where 

 they themselves first began life. Therefore, 

 when we find an animal leaving the haunt in 

 which the greater part of its life is passed, to 

 bring forth its young in quite a different one, 

 we have good grounds for believing that its 

 ancestors once had their home in the haunt to 

 which it returns. 



But there is a difficulty here which must be 

 faced. There are some cases in which the 

 youthful stages are passed in a haunt which 

 was certainly not the original headquarters. 

 A good illustration of this may be found in 

 insects like May-flies and Dragon-flies, Caddis- 

 flies and Alder-flies, Gnats and Harlequin-flies, 



