a eet 4 ‘ : = ee 7 a 
. 7 4 74 2 i et 
18 AN OUTLINE OF THE THEORY. 
discover prey or escape from an enemy better than their 
fellows. Among plants the smallest differences may be 
useful or the reverse. The earliest and strongest shoots 
may escape the slug; their greater vigor may enable them 
to flower and seed earlier in a wet autumn; plants best 
armed with spines or hairs may escape being devoured ; 
those whose flowers are most conspicuous may be soonest 
fertilized by insects. We can not doubt that, on the whole, 
any beneficial variations will give the possessors of it a 
greater probability of living through the tremendous or- 
deal they have to undergo. There may be something 
left to chance, but on the whole the fittest will survive.” 
“Darwinism” p. 7). 
The same writer gives a probable instance of the 
working of Natural Selection in the origin of certain 
aquatic birds called dippers. He says: “An excellent ex- 
ample of how a limited group of species has been able 
to maintain itself by adaptation to one of these ‘vacant 
places’ in Nature, is afforded by the curious little birds 
called dippers or water-ouzels, forming the genus Cinclus 
and the family Cinclidae of naturalists. These birds are 
something like small thrushes, with very short wings and 
tail, and very dense plumage. They frequent, exclusive- 
ly, mountain torrents in the northern hemisphere, and ob- 
tain their food entirely in the water, consisting, as it does, 
of water-beetles, caddis-worms, and other insect-larvae, 
as well as numerous small fresh-water shells. These 
birds, although not far removed in structure from thrush- 
es and wrens, have the extraordinary power of flying 
under water; for such, according to the best observers, 
is their process of diving in search of their prey; their 
dense and somewhat fibrous plumage retaining so much 
air that the water is prevented from touching their bodies 
or even from wetting their feathers to any great extent. 
Their powerful feet and long curved claws enable them 
