158 



DOMESTIC PIGEONS. 



Cl!AJ>. V 



and short-faced Tumblers. The remaining domestic forms might 

 have been included in the same genus with the wild rock-pigeon. 



Individual Variability ; Variations of a remarkable nature. 



The differences which we have as yet considered are charac- 

 teristic of distinct breeds ; but there are other differences, either 

 confined to individual birds, or often observed in certain breeds 

 but not characteristic of them. These individual differences are 

 of importance, as they might in most cases be secured and 

 accumulated by man's power of selection ; and thus an existing 

 breed might be greatly modified or a new one formed. Fanciers 

 notice and select only those slight differences which are exter- 

 nally visible ; but the whole organisation is so tied together bv 

 correlation of growth, that a change in one part is frequently 

 accompanied by other changes. For our purpose, modifications 

 of all kinds are equally important, and, if affecting a part which 

 does not commonly vary, are of more importance than a modi- 

 fication in some conspicuous part. At the present day any visible 

 deviation of character in a well-established breed is rejected as 

 a blemish ; but it by no means follows that at an early period, 

 before well-marked breeds had been formed, such deviations 

 would have been rejected ; on the contrary, they would have 

 been eagerly preserved as presenting a novelty, and would then 

 have been slowly augmented, as we shall hereafter more clearly 

 see, by the process of unconscious selection. 



I have made numerous measurements of the various parts of the body in 

 the several breeds, and have hardly ever found them quite the same in 

 birds of the same breed, — the differences being greater than we commonly 

 meet with in wild species. To begin with the primary feathers of the 

 wing and tail ; but I may first mention, as some readers may not be aware 

 of the fact, that the number of the primary wing and tail feathers in wild 

 birds is generally constant, and characterises, not only whole genera, 

 but even whole families. When the tail feathers are unusually numerous, 

 as for instance in the swan, they are apt to be variable in number ; but this 

 does not apply to the several species and genera of the Columbidse, which 

 never (as far as I can hear) have less than twelve or more than sixteen 

 tail-feathers ; and these numbers characterise, with rare exception, whole 

 sub-families. 27 The wild rock-pigeon has twelve tail-feathers. With Fan- 



2 " ' Coup-d'ceil sur l'Ordre des 

 Pigeons,' par C. L. Bonaparte (Comptes 



Eendus), 1854-55. Mr. Blyth, in 

 ' Annals of Nat. Hist.,' vol. xix., 1847, 



