THE BELFAST ADDRESS 187 



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 organization 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 selec- 

 tion 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, siiill, 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 surround- 

 ing conditions will infallibly give way to those that are 

 most competent. To use a familiar proverb, the weakest 



