280 STUDY OF NATURAL HISTORY. 



and no axiom requires to be more impressed upon 

 the mind of the true follower of science, that a 

 natural arrangement will stand any test. The two 

 groups in question may be characterised by their 

 external forms ; and yet we see that the arrangement 

 thus produced and founded on the perfect insect, 

 developes the same theory of the variation of meta- 

 morphosis which pervades the whole of the order. 



(190.) We have now attempted to point out the 

 chief considerations which should influence the 

 naturalist in his choice of characters ; whereby he 

 may define, with brevity and perspicuity, the nu- 

 merous groups into which nature has divided the 

 animal kingdom ; or which it is necessary for 

 us to keep in distinct allotments, until their true 

 station in the scale of being is better understood. 

 Characters, founded upon the circumstances here 

 noted, are independent of all theory ; inasmuch as 

 they will repose upon facts of structure or of eco- 

 nomy, which, in any system, must be kept distinct. 

 In what sense they are to be used, or rather, to what 

 description of groups they are applicable, is another 

 question, which can only be solved by great ex- 

 perience, and by understanding the principles of 

 variation in the different classes of the animal 

 kingdom. Our present business is merely to point 

 them out as solid materials for effecting scientific 

 arrangement, leaving their application to the judg- 

 ment and prudence of those who are competent 

 to use them. Our own views, resulting from an at- 

 tentive consideration of all these phenomena, will 

 form the subject of a succeeding volume. We are 

 not now either explaining or advocating any parti- 



