ISOLATION oi TIN-: MALI: 65 



of that method which we observe in the 

 periodical returns of the Hunting or the Finch, 

 it may be thought that needless importance 

 is being attached to an episode in their lives 

 which is quite intelligible in terms of a feeble 

 response determined by a dawning organic 

 change. While it may be quite intelligible in 

 such terms it is not thereby explained ; for 

 every response must have as its antecedent an 

 inherited connection in the nervous system 

 determined on biological grounds. Besides, 

 these early periodic returns conform in general 

 to the type of behaviour displayed by other 

 species, the males of which return to their breed- 

 ing grounds many weeks before the real business 

 of reproduction begins. Are we then justified in 

 regarding them as accidents of the developing 

 situation ? Are we not rather bound to admit 

 that they have some definite biological end to 

 serve ? 



These examples show that the males of many 

 species reverse their mode of life at the com- 

 mencement of the breeding season and proceed 

 to isolate themselves, each one in a definitely 

 delimited area. 



There are three ways in which we may 

 attempt to interpret this particular mode of 

 male behaviour. We may regard it as an 

 accidental circumstance, nowise influencing the 

 course of subsequent procedure; or, appealing 

 to the law of habit formation, we may 

 regard it as an individual acquirement; or 



