-i :< i HIM; TERRITORY 3 



fosteml, and protected from molestation for 

 periods oi' varying lengths, the actual discharge 

 of the sexual function marks but one stage in a 

 process which can only succeed if all the con- 

 tributory factors adequately meet the essential 

 conditions of the continuance of the species. 



Securing a territory is then part of a process 

 which has for its goal the successful rearing 

 of offspring. In this process the functioning 

 of the primary impulse, the acquirement of a 

 place suitable for breeding purposes, the advent 

 of a female, the discharge of the sexual func- 

 tion, the construction of the nest, and the 

 rearing of offspring follow one another in 

 orderly sequence. But since we know so little 

 of the organic changes which determine sexual 

 behaviour, and have no means of ascertaining 

 the nature of the impulse which is first 

 aroused, we can only deal with the situation 

 from the point at which the internal organic 

 changes reflect themselves in the behaviour to 

 a degree which is visible to an external observer. 

 That point is reached when large numbers of 

 species, forsaking the normal routine of exist- 

 ence to which they have been accustomed for 

 some months, suddenly adopt a radical change 

 in their mode of behaviour. How is this change 

 made known to us ? By vast numbers of 

 individuals hurrying from one part of the globe 

 to another, from one country to another, and 

 even from mid-ocean to the coasts ; by detach- 

 ments travelling from one district to another ; 

 by isolated individuals deserting this place for 



B 



