Chap. VI. MANNER OF FORMATION OF RACES. 235 



is followed methodically when the fancier tries to improve 

 and modify a breed according to a prefixed standard of excel- 

 lence; or he acts unmethodically and unconsciously, by 

 merely trying to rear as good birds as he can, without any 

 wish or intention to alter the breed. The progress of 

 selection almost inevitably leads to the neglect and ultimate 

 extinction of the earlier and less improved forms, as well as 

 of many intermediate links in each long line of descent. 

 Thus it has come to pass that most of our present races are 

 so marvellously distinct from each other, and from the 

 aboriginal rock -pigeon. 



