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trolled, are by constitution more tractile (and possess, 

 therefore, more decided powers for aberration) than the 

 rest. Whether traces of design may be recognized in 

 this circumstance, or whether those forms were originally 

 selected by man on account of their phabihty, it is not 

 for me to conjecture j nevertheless, the first of these in- 

 ferences is the one which J should, myself, be a priori 

 inclined to subscribe to. 



In examining, however, this enigma, of the limits 

 within which variation is (as such) to be recognized ; it 

 should never be forgotten, that it is possible for those 

 boundaries to be absolutely and critically marked out 

 even where we are not able to discern them : so that the 

 difficulty which a few domesticated creatures of a singu- 

 larly flexible organization present, should not unneces- 

 sarily predispose us to dispute the question in its larger 

 and more general bearings. Nor should we be unmiad- 

 ful that (as Sir Charles LyeU has aptly suggested) " some 

 mere varieties present greater difierences, inter se, than 

 do many individuals of distinct species ;" for it is a truth 

 of considerable importance, and one which may help us 

 out of many an apparent dilemma. 



But, whatever be the several ranges within which the 

 members of the organic creation are free to vary; we 

 are positively certain that, unless the definition of a species, 

 as involving relationship, be more than a delusion or ro- 

 mance, their circumferences are of necessity real, and 

 must be indicated somewhere, — as strictly, moreover, and 

 rigidly, as it is possible for anything in Nature to be 



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