220 TBANS1TIONS OF OEGAXIC BEINGS. [Chap. YI 



material for us, whether habits generally change first 

 and structure afterwards ; or whether slight modifi- 

 cations of structure lead to changed habits ; both 

 probably often occurring almost simultaneously. Of 

 cases of changed habits it will suffice merely to allude 

 to that of the many British insects which now feed on 

 exotic plants, or exclusively on artificial substances. 

 Of diversified habits innumerable instances could be 

 given : I have often watched a tyrant flycatcher (Sauro- 

 phagus sulphuratus) in South America, hovering over 

 one spot and then proceeding to another, like a kestrel, 

 and at other times standing stationary on the margin of 

 water, and then dashing into it like a kingfisher at a 

 fish. In our own country the larger titmouse (Parus 

 major) may be seen climbing branches, almost like a 

 creeper ; it sometimes, like a shrike, kills small birds 

 by blows on the head ; and I have many times seen . 

 and heard it hammering the seeds of the yew on a 

 branch, and thus breaking them like a nuthatch. In 

 North America the black bear was seen by Hearne 

 swimming for hours with widely open mouth, thus 

 catching, almost like a whale, insects in the water. 



As we sometimes see individuals following habits 

 different from those proper to their species and to the 

 other species of the same genus, we might expect that 

 such individuals would occasionally give rise to new 

 species, having anomalous habits, and with their 

 structure either slightly or considerably modified from 

 that of their type. And such instances occur in nature. 

 Can a more striking instance of adaptation be given 

 than that of a woodpecker for climbing trees and seizing 

 insects in the chinks of the bark ? Yet in North 

 America there are woodpeckers which feed largely on 



