834 LUTHER BURBANK 



plumage habitually throughout the year. But 

 these are birds of predacious habits that are 

 little subject to the attacks of enemies, and it 

 has been shown that the white color, or bluish 

 white, tends to make the birds inconspicuous 

 from the viewpoint of the fish that are their 

 prey. 



So in the case of the tiny snow bunting and of 

 pelicans and herons, the white color of the plum- 

 age is seen to be advantageous to its wearer and 

 hence is easily explained according to the prin- 

 ciple of natural selection. The same is true of 

 the white plumage assumed by those species of 

 grouse and ptarmigan that winter in the Arctic 

 or sub- Arctic regions ; and contrariwise, the pig- 

 mented coats of the vast majority of the birds 

 and animals of temperate zones are accounted for 

 on the same principle. 



But just why the fruits of plants should almost 

 universally be pigmented seems at first not quite 

 so clear. It is ordinarily supposed to be advan- 

 tageous for a plant to have its fruit made visible 

 to the birds and animals, that the aid of these 

 creatures may be gained in disseminating the 

 seed. And it must be obvious that a white black- 

 berry would be as conspicuous in the woodlands 

 where this vine grows as are the jet black berries 

 of the ordinary type. 



