Feet and Legs 361 



in which birds have inherited the earth. When we realize 

 the immense advantage which the power of flight gives 

 to them, we do not marvel at this remarkable distribu- 

 tion, but the more we think about it the more wonders 

 appear. The utmost efforts which man has made to 

 reach the North Pole have shown flocks of birds winging 

 their way still farther to the North, heedless of the ter- 

 rible cold. In the heat of deserts and the sweltering 

 jungles of the tropics, birds find congenial haunts and 

 abundant food. Thousands of miles out at sea, on the 

 highest mountains, and even in dark underground tun- 

 nels; the whole day — twilight, midnight, and dawn, — 

 all have been conquered by these tireless, energetic feath- 

 ered ones. 



When we see a large collection of birds, we can appre- 

 ciate how they are adapted to such varying conditions 

 of temperature, of moisture, of light, and of altitude. 

 Their bodies, wings, legs, feet, and tails — in fact every 

 organ and member is of all sizes and shapes, and shows to 

 what condition of life the individual is suited. But when 

 we come to know birds better, and we realize that there 

 are wheels within wheels, that behind these very evident 

 divisions into Families and Orders there are lesser groups, 

 among the members of which the competition is no less 

 keen, we look for and find gentler gradations and adapta- 

 tions which, in their way, are more to be wondered at 

 than the larger, more radical differences; for these birds 

 have changed their habits and haimts without waiting 

 for Nature to adjust their wings or their feet. They have 

 taken the initiative as it were, and, like a man of letters 



