CHAP. I.] CIRCUMSTANCES FAVOURABLE TO SELECTION. 27 



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 turbit now does the upper 

 part of its oesophagus, a habit which is disregarded by all fanciers, 

 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 extremely small 

 differences, and it is in human nature to fancy 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 which is now set on 

 them, after several breeds have fairly been established. It is known 

 that with pigeons many slight variations now occasionally appear, 

 but these are rejected as faults or deviations from the standard of 

 perfection in each breed. The common goose has not given rise to 

 any marked varieties ; hence the Toulouse and the common breed, 

 which differ only in colour, that most fleeting of characters, have 

 lately been exhibited as distinct at our poultry -shows. 



These views appear to explain what has sometimes been noticed 

 namely, that we know hardly anything about the origin or history 

 of any of our domestic breeds. But, in fact, a breed, like a dialect 

 of a language, can hardly be said to have a distinct origin. A man 

 preserves and breeds from an individual with some slight deviation 

 of structure, or takes more care than usual in matching his best 

 animals, and thus improves them, and the improved animals slowly 

 spread in the immediate neighbourhood. But they will as yet hardly 

 have a distinct name, and from being only slightly valued, their 

 history will have been disregarded. When further improved by the 

 same slow and gradual process, they will spread more widely, and 

 will be recognized as something distinct and valuable, and will then 

 probably first receive a provincial name. In semi-civilised countries, 

 with little free communication, the spreading of a new sub-breed 

 would be a slow process. As soon as the points of value are once 

 acknowledged, the principle, as I have called it, of unconscious 

 selection will always tend, perhaps more at one period than at 

 another, as the breed rises or falls in fashion, perhaps more in one 

 district than in another, according to the state of civilisation of the 

 inhabitants, slowly to add to the characteristic features of the 

 breed, whatever they may be. But the chance will be infinitely 

 small of any record having been preserved of such slow, varying, 

 and insensible changes. 



Circumstances favourable to Man's Power of Selection. 



I will now say a few words on the circumstances, favourable, or 

 the reverse, to man's power of selection. A high degree of variability 

 is obviously favourable, as freely giving the materials for selection 



