THE BELFAST ADDRESS. 175 



in the way of producing variation. He associated him- 

 self with pigeon-fanciers bought, begged, kept, and 

 observed every breed that he could obtain. Though de- 

 rived from a common stock, the diversities of these 

 pigeons were such that 'a score of them might be 

 chosen which, if shown to an ornithologist, and he were 

 told that they were wild birds, would certainly be 

 ranked by him as well-defined species/ The simple 

 principle which guides the pigeon-fancier, as it does the 

 cattle-breeder, is the selection of some variety that 

 strikes his fancy, and the propagation of this variety 

 by inheritance. With his eye still directed to the 

 particular appearance which he wishes to exaggerate, 

 he selects it as it reappears in successive broods, and 

 thus adds increment to increment until an astonishing 

 amount of divergence from the parent type is effected. 

 The breeder in this case does not produce the elements 

 of the variation. He simply observes them, and by 

 selection adds them together until the required result 

 has been obtained. * No man,' says Mr. Darwin, ' would 

 ever try to make a fantail till he saw a pigeon with a 

 tail developed in some slight degree in an unusual 

 manner, or a pouter until he saw a pigeon with a crop 

 of unusual size.' Thus nature gives the hint, man acts 

 upon it, and by the law of inheritance exaggerates the 

 deviation. 



Having thus satisfied himself by indubitable facts 

 that the organisation of an animal or of a plant (for 

 precisely the same treatment applies to plants) is to 

 gome extent plastic, he passes from variation under 

 domestication to variation under nature. Hitherto we 

 have dealt with the adding together of small changes 

 by the conscious selection of man. Can Nature thus 

 select? Mr. Darwin's answer is, ' Assuredly she can.' 

 The number of living things produced is far in excess 



