MATING CONTROLLED 175 



separation ; in the second, there will he nothing 

 in the external environment to induce them to 

 remain in any particular spot. Now if we turn 

 to any common species and observe the sequence 

 of events in the life of different pairs, we shall 

 find that pairing is seldom followed by an 

 immediate attempt to build ; that an interval 

 of inactivity is the rule rather than the excep- 

 tion, and that this interval varies in different 

 species, in different individuals, and in different 

 seasons. Our imaginary male and female will 

 therefore be faced with considerable difficulty ; 

 for with nothing in the external environment to 

 attract them and with no restriction imposed 

 upon the direction or extent of their flight, their 

 union will continue to be, as it began by being, 

 fortuitous. Next, let us consider their position 

 were a disposition to establish a territory to 

 form part of the inherited nature of the male. 

 Each one will then be free to seek food when 

 and where it wills and to associate with other 

 individuals without the risk of permanent 

 separation from its mate ; and, no matter how 

 long an interval may elapse between mating and 

 nest-building, each one will be in a position to 

 find the other when the appropriate moment for 

 doing so arrives. Hence, while preserving 

 freedom of movement for each individual, the 

 territory will render their future, as a pair, 

 secure. 



No doubt the course of behaviour, as we 

 observe it to-day in the lives of many species, is 

 the outcome of, rather than the condition which 



