9280 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- 
