28 THE ORIGIN OF SPECIES 



for their own food, at least during certain seasons. And in two 

 countries very differently circumstanced, individuals of the same 

 species, having slightly different constitutions or structure, would 

 often succeed better in the one country than in the other; and 

 thus by a process of "natural selection," as will hereafter be more 

 fully explained, two sub-breeds might be formed. This, perhaps, 

 partly explains why the varieties kept by savages, as has been re- 

 marked by some authors, have more of the character of true spe- 

 cies than the varieties kept in civilized countries. 



On the view here given of the important part which selection by 

 man has played, it becomes at once obvious, how it is that our do- 

 mestic races show adaptation in their structure or in their habits 

 to man's wants or fancies. We can, I think, further understand the 

 frequently abnormal character of our domestic races, and likewise 

 their differences being so great in external characters, and rela- 

 tively so slight in internal parts or organs. Man can hardly select, 

 or only with much difficulty, any deviation of structure excepting 

 such as is externally visible; and indeed he rarely cares for what 

 is internal. He can never act by selection, excepting on variations 

 which are first given to him in some slight degree by nature. No 

 man would ever try to make a fantail till he saw a pigeon with a 

 tail developed in some slight degree in an unusual manner, or a 

 pouter till he saw a pigeon with a crop of somewhat unusual size ; 

 and the more abnormal or unusual any character was when it first 

 appeared, the more likely it would be to catch his attention. But 

 to use such an expression as trying to make a fantail is, I have no 

 doubt, in most cases utterly incorrect. The man who first selected 

 a pigeon with a slightly larger tail, never dreamed what the de- 

 scendants of that pigeon would become through long-continued, 

 partly unconscious and partly methodical, selection. Perhaps the 

 parent-bird of all fantails had only fourteen tail-feathers some- 

 what expanded, like the present Java fantail, or like individuals 

 of other and distinct breeds, in which as many as seventeen tail- 

 feathers have been counted. Perhaps the first pouter-pigeon did 

 not inflate its crop much more than the turbid now does the upper 

 part of its oesophagus — a habit which is disregarded by all fan- 

 ciers, as it is not one of the points of the breed. 



Nor let it be thought that some great deviation of structure 

 would be necessary to catch the fancier's eye; he perceives ex- 

 tremely small differences, and it is in human nature to value any 

 novelty, however slight, in one's own possession. Nor must the 

 value which would formerly have been set on any slight differences 

 in the individuals of the same species, be judged of by the value 



