Chap. VI. MANNER OF FORMATION OF RACES. 229 



two fanciers have Rxactly the same taste, and consequently 

 no two, in choosing and carefully matching their birds, 

 prefer or select exactly the same. As each man naturally 

 admires his own birds, he goes on continually exaggerating 

 by selection whatever slight peculiarities they may jiosseas 

 This will more especially happen with fanciers living in 

 different countries, who do nut compare their stocks or aim 

 at a common standard of perfection. Thus, when a mere 

 strain has once been formed, unconscious selection steadily 

 tends to augment the amount of difference, and thus converts 

 the strain into a sub-breed and this ultimately into a well- 

 marked breed or race. 



The principle of correlation of growth should never be lost 

 sight of. Most pigeons have small feet, ai:)parently caused 

 by their lessened use, and from correlation, as it would 

 appear, their beaks have likewise become reduced in length. 

 TJie beak is a conspicuous organ, and, as soon as it had thus 

 become perceptibly shortened, fanciers would almost certainly 

 strive to reduce it still more by the continued selection of 

 birds with the shortest beaks ; whilst at the same time other 

 fanciers, as we know has actually been the case, would in 

 other sub-breeds, strive to increase its length. With the 

 increased length of the beak, the tongue becomes greatly 

 lengthened, as do the eyelids with the increased development 

 of the eye- wattles ; with the reduced or increased size of the 

 feet, the number of the scutellaj vary ; with the length of the 

 wing, the number of the primary wing-feathers differ ; and 

 with the increased length of the body in the jiouter the 

 number of the sacral vertebrae is augmented. These im- 

 portant and correlated differences of structure di not in- 

 variably characterise any breed ; but if they had been 

 attended to and selected with as much care as the more 

 conspicuous external differences, there can hardly be a doubt 

 that they would have been rendered constant. Fanciers 

 could assuredly have made a race of Tumblers with nine 

 instead of ten primary wing-feathers, seeing how often the 

 number nine appears without any wish on their part, and 

 indeed in the case of the white-winged varieties in opposition 

 to their wish, in a similar manner, if the vertebrae had 



