Chap. VI. M.\NNER OF FORMATION OF R.\CES, 231 



into slightly different sub-breeds, such as the common 

 English Tumbler, the Dutch Eoller, the Glasgow House- 

 tumbler, and the Long-faced Beard Tumbler, &c. ; and in the 

 course of centuries, unless fashions greatly change, these sub- 

 breeds will diverge through the slow and insensible process 

 of unc mscious selection, and become modified, in a greater 

 and greater degree. After a time the perfectly graduated 

 links which now connect all the>e sub-breeds together, will 

 be lost, for there would be no object and much difficulty in 

 retaining such a host of intermediate sub-varieties. 



The principle of divergence, together with the extinction 

 of the many previously existing intermediate forms, is so 

 important for understanding the origin of domestic races, as 

 well as of species in a state of nature, that I will enlarge a 

 little more on this subject. Our third main group includes 

 Carriers, Barbs, and Kunts, which are plainly related to one 

 another, yet wonderfully distinct in several important cha- 

 racters. According to the view given in the last cliapter, 

 these three races have probably descended from an unknown 

 race having an intermediate character, and this race from the 

 rock-pigeon. Their characteristic differences are believed to 

 be due to different breeders having at an early period admired 

 different points of structure ; and then, on the acknowledged 

 principle of admiring extremes, having gone on breeding, 

 without any thought of the future, as good birds as they 

 could, — Carrier- fanciers preferring long beaks with much 

 wattle, — Barb-fanciers preferring short thick beaks with 

 much ej^e-wattle, — and Runt-fanciers not caring about the 

 beak or wattle, but only for the size and weight of the body. 

 This process would have led to the neglect and final extinc- 

 tion of the earlier, inferior, and intermediate birds ; and thus 

 it has come to pass, that in Europe these three races are now 

 so extraordinarily distinct from each other. But in the East, 

 whence they were originally brought, the fashion has been 

 different, and we there see breeds which connect the highlj 

 modified English Carrier with the rock-pigeon, and others 

 which to a certain extent connect Carriers and Runts. Look- 

 ing back to the time of Aldrovandi, we find tliat there 

 existed in Europe, before the year 1600, four breeds which 



