220 STUDY OF NATURAL HISTORY. 



that these are the very groups, above all others, 

 wherein the principles of enquiry we are now re- 

 commending can be most successfully and most 

 easily pursued ; and for this purpose, as such, they 

 should consequently be selected. When, therefore, 

 we can draw any general deductions from the 

 contents of several such groups, whether as re- 

 gards the mode of variation in their subordinate 

 forms, the characters of the forms themselves, or 

 their definite number, we may rest assured of 

 having committed no great error in their natural 

 arrangement ; and may safely assume the inductions 

 thus obtained, as instruments to facilitate our further 

 progress. Having now stated those primary con- 

 siderations which appear necessary to determine, on 

 sound principles of inductive science, the two lowest 

 groups of nature, namely, sub-genera and genera, 

 we may proceed a step further, and enquire into 

 higher combinations. 



(155.) The groups next in rank to genera,, modern 

 naturalists agree in calling sub-families. The name, 

 however, has nothing to do with our present object, 

 further than that it is necessary to give some 

 designation to groups which are next in rank, 

 or in comprehensiveness, to those last discussed. 

 The determination, therefore, of a group of this 

 sort, — no matter by what name we choose to call 

 it, — must be regulated by the law we set out with 

 assuming ; that is, by the union of a certain number 

 of genera, which, thus combined, produce a circular 

 series. Here, again, the question of numbers 

 arises. Now, bearing in mind, that the greater the 

 degree of harmony and unity we can produce in our 



