26 



In spite of this severe distinction, however, which I 

 would urge between the insect aborigines of a country 

 and those which (whether by compulsion or not) have 

 colonized it, and of the preference which (as just stated) 

 must be given to the latter whilst investigating the con- 

 trolling principles of aberration, I would not wish to 

 reject in toto the testimony which the former likewise 

 may indirectly furnish, especially under the present 

 section, in which climatal causes on a large scale have 

 to be taken into account. True it is that we cannot 

 hope to descry physical results amongst phenomena 

 which are due to the creative force alone ; yet we may, 

 in the contemplation of them, recognize such an amount 

 of design, or a primary adaptation to conditions from 

 without, as shall afford, through its permanence and 

 method, fresh presumptive evidence that the " conditions" 

 themselves may have some inherent modifying power of 

 their own on the aggressors from other districts, in which 

 a contrary influence may perchance prevail, and for the 

 overspreading of which they were, in the beginning, 

 more peculiarly constituted and ordained. 



It has been already mentioned (and, despite the ex- 

 ceptional cases which are to be found, it is in a general 

 sense true), that the splendour and extravagance of the 

 insect world attain their maximum within the tropics ; 

 and that the nearer we approach the central heat, the 

 more and more unmistakeable is the existence of this 

 law. It has been also hinted, that when viewed on a 

 very extensive scale, we shall not derive much direct 



