Aves. 209 



dry, pithy remains of this pulp are found in the quill, which 

 is now narrowed at the base, but still shows an aperture. 



Kinds of Feathers. There are four principal kinds 

 of feathers : ( I ) The quills found on the wings and tail. 

 (2) The contour feathers, which have the same general 

 structure as the quills, but are smaller, and lie close to 

 the body. They protect the body from bruises, and also 

 from cold, being the very best of non-conductors of heat. 

 Their mode of overlapping serves admirably for shedding 

 rain and for retaining the heat when flying through cold 

 air. (3) Downy feathers, which differ from the above , in 

 not having the barbs fastened together by hooked barbules ; 

 the result is a loose, soft feather, well suited for retaining 

 heat. These feathers, when present, are inside the contour 

 feathers, where we should expect to find them. The young 

 pigeon has downy feathers, but they disappear in the adult. 

 (4) The pinfeathers are fine, hairlike feathers, usually left 

 after the pigeon is plucked, and usually removed from fowls 

 by singeing. They show that they are feathers by a little 

 tuft of barbs at the tip. 



Distribution of Feathers. Feathers are not evenly dis- 

 tributed over the surface of the body ; but there are certain 

 areas from which they grow, and certain other areas from 

 which feathers never grow. By separating the feathers on 

 a bird's breast it may readily be seen that no feathers de- 

 velop there. There are also bare places on the sides of the 

 neck and in other places ; but the length of the feathers 

 and their mode of overlapping cover these bare spots, so 

 that most people hardly know of their existence. 



The Pigeon's Wing. The wing, like our arm, consists of 

 three parts, the arm, forearm, and hand. The similarity 

 of the first and second of these to the corresponding part 

 of our arms is so evident that it needs no explanation. The 



