6 INTRODUCTION 



the purpose of the theory I shall give ex- 

 pression to this behaviour in terms of that 

 theory, and speak of it as a disposition to 

 secure a territory, using the word disposition, 

 which has been rendered current in recent dis- 

 cussion, for that part of the inherited nature 

 which has been organised to subserve a specific 

 biological purpose — strict compliance with the 

 rules of psychological analysis requires a simpler 

 definition ; let us therefore say " disposition to 

 remain in a particular place in a particular 

 environment." 



But even granting that this disposition 

 forms part of the hereditary equipment of 

 the bird, how is the process of reproduction 

 furthered ? The mere fact of remaining in or 

 about a particular spot cannot render the attain- 

 ment of reproduction any less arduous, and may 

 indeed add to the difficulties, for any number 

 of individuals might congregate together and 

 mutually affect one another's interests. A 

 second disposition comes, however, into func- 

 tional activity at much the same stage of sexual 

 development, and manifests itself in the male's 

 intolerance of other individuals. And the two 

 combined open up an avenue through which 

 the individual can approach the goal of re- 

 production. In terms of the theory I shall 

 refer to this second disposition as the one 

 which is concerned with the defence of the 

 territory. 



Broadly speaking, these two dispositions may 

 be regarded as the basis upon which the breed- 



