INSECTS IN GENERAL. 99 



Such is an outline of the system of M. Latreille, from 

 which he conceives that geography may derive sound 

 advantages. It may thereby be determined to which of the 

 two hemispheres naturally belong many islands situated on 

 their limits. Such considerations, he also thinks, may be 

 useful to mineralogists and geologists. We see, for instance, 

 that the insects,, and even the plants of those countries by 

 which the basin of the Mediterranean is circumscribed, and 

 also those of the Black and Caspian Seas, singularly re- 

 semble each other as to the genera and families in which 

 those productions are grouped. Such relations seem to fa- 

 vour the opinion of naturalists, that the latest uncovered 

 countries have been those which were formerly bathed by 

 the waters of the ocean. 



The increasing progression of the intensity and duration 

 of caloric, has a very great influence on the volume and the 

 development of the mucous tissue of insects and arachnida. 

 The more, in general, that we advance towards the equi- 

 noxial regions, the more we find of species remarkable for 

 their size, for the inequalities and prominences of their 

 bodies, and for the variety of their colours. The increase of 

 light tends to convert yellow into red and orange. The 

 diurnal butterflies of our mountains have usually the ground 

 of their wings white, or of a brown more or less deep. Such 

 observations, properly followed up, would greatly assist in 

 the distinction of species and varieties. 



Having considered the general structure, the functions, 

 and the geographical distribution of insects, we shall indulge 

 in a few remarks on that most interesting of all subjects, the 

 character of their intellectual faculties. In this point of 

 view, although the labours of insects appear to announce a 

 degree of industry of which the superior classes of animals 

 presents us with few examples, yet there can be no compari- 

 son between them and the latter as to extent of intellect. 



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