THE BELFAST ADDRESS. 175 



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. 1 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 

 some 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 

 of the number that can be supported ; hence at some 

 period or other of their lives there must be a struggle 

 for existence. And what is the infallible result ? If 

 one organism were a perfect copy of the other in regard 

 to strength, skill, and agility, external conditions would 

 decide. But this is not the case. Here we have the 

 fact of variety offering itself to nature, as in the former 

 instance it offered itself to man ; and those varieties 

 which are least competent to cope with surrounding 

 conditions will infallibly give way to those that are 

 most competent. To use a familar proverb, the weak- 



