98 Animal Life and Intelligence. 



small and weak birds. The smaller and weaker coal-tit- 

 mouse has adopted a more vegetarian diet, eating seeds as 

 well as insects, and feeding on the ground as well as among 

 trees. The delicate little blue titmouse, with its very small 

 bill, feeds on the minutest insects and grubs, which it 

 extracts from crevices of bark and from the buds of fruit 

 trees. The marsh-titmouse, again, has received its name 

 from the low and marshy localities it frequents ; while the 

 crested titmouse is a Northern bird, frequenting especially 

 pine forests, on the seeds of which trees it partially feeds. 

 Then, again, our three common pipits the tree-pipit, the 

 meadow-pipit, and the rock-pipit, or sea-lark have each 

 occupied a distinct place in nature, to which they have 

 become specially adapted, as indicated by the different 

 form and size of the hind toe and claw in each species. 

 So the stone-chat, the whin-chat, and the wheat-ear are all 

 slightly divergent forms of one type, with modifications in 

 the shape of the wing, feet, and bill adapting them to 

 slightly different modes of life." * There is scarcely a 

 genus that does not afford examples of divergent species. 

 The question then naturally occurs How have these 

 divergent forms escaped the swamping effects of inter- 

 crossing ? 



That perfectly free intercrossing, between any or all of 

 the individuals of a given group of animals, is, so long as 

 the characters of the parents are blended in the offspring, 

 fatal to divergence of character, is undeniable. Through 

 the elimination of less favourable variations, the swiftness, 

 strength, and cunning of a race may be gradually improved. 

 But no form of elimination can possibly differentiate the 

 group into swift, strong, and cunning varieties, distinct 

 from each other, so long as all three varieties freely inter- 

 breed, and the characters of the parents blend in the off- 

 spring. Elimination may and does give rise to progress in 

 any given group as a group ; it does not and cannot give 

 rise to differentiation and divergence, so long as interbreed- 

 ing with consequent interblending of characters be freely 



* " Darwinism," p. 108. 



