INTRODUCTORY REMARKS. XXXIX 



for certain forms (when systematically acted upon by the skill and 

 intellect of man) is so extremely wide, in comparison with that al- 

 lowed in the case of others, as to be practically almost infinite*. And 

 consequently, if it ever should be shown that we have fallen largely 

 into error in regarding certain closely allied organisms as specifically 

 distinct, I would surmise that it proves absolutely nothing except 

 the fact of our own ignorance as to where the proper lines of demar- 

 cation are to be drawn. But that those lines have an (abstract) ex- 

 istence somewhere I take for granted ; and it is the province of the 

 naturalist to endeavour to obtain an approximate idea, so far as may 

 be, and so far as his limited experience will permit, of their several 

 positions. 



After these remarks I shall not be misunderstood when I express 

 my belief, that some of the forms enumerated in this volume, which 

 differ but slightly (though permanently) from those of European lati- 

 tudes, will perhaps prove to be but local phases of the latter brought 

 about either by isolation, or a difference in the exact chemical pro- 

 perties of the plants on which they have long been compelled to sub- 

 sist. And hence, for instance, when I find attached to the Pinus 

 canariensis Coleoptera which recede but minutely from those which 

 destroy the fir trees of more northern countries, I cannot but feel 

 it probable even whilst (on account of the fixedness of their cha- 

 racters) registering them as distinct that they do in reality repre- 



* It seems often assumed that if variation is acknowledged to be " infinite," 

 we tacitly imply that it must needs be also monstrous ; but this appears to me a 

 very gratuitous conclusion. Although common circumstances are sometimes apt 

 to be overlooked, they nevertheless will frequently supply evidence more satis- 

 factory than we can gather elsewhere ; and even in the present case, therefore, 

 we may perhaps venture to appeal to them. Although incapable of ocular de- 

 monstration (for it is a truth of reason and not of sense), there are probably few 

 reflecting minds which would reject the dogma that no two human beings ever 

 have existed, or ever will exist, which are absolutely alike in every single part, 

 and combination, of their entire structure. Yet, in spite of this individual vari- 

 ability, which is strictly infinite, we are not driven to believe in forms which are 

 in any degree " monstrous." On the contrary, so unmistakeably are they in- 

 cluded within the morphotic limits assigned for the human frame, that (whilst 

 those "limits" are by us undefinable, and the variations infinite) the forms them- 

 selves seldom strike us as even extraordinary, and therefore never (a fortiori) as 

 monstrous. And if this be true for "individual variability," it is true also for 

 " variation " (as commonly understood by that term) ; for distinct varieties are as 

 much a fact in the human family as " individual variability." From which I 

 infer that variation may have full play, and be by us undefinable, and yet posi- 

 tively restrained within the limits which were imposed upon it aboriginally for 

 each separate species; and, therefore, conversely, that a species may be inde- 

 finitely plastic, and yet remain true to its type. Those naturalists therefore 

 who tell us that we have no logical right to believe in " species " (as hitherto 

 enunciated) whilst we are unable to define their limits, merely appeal to an impos- 

 sibility, or our want of omniscience, as the evidence for overthrowing a fun- 

 damental truth. 



