Feathers 



21 



to be entirely naked; but a closer inspection shows 

 scanty tufts of down scattered irregularly over the body. 

 This, like the set of milk-teeth in mammals, is useful 

 only for a time, and is later pushed out by the second 

 or true plumage. Even more numerous than the down- 



FiG. 10. — Brown Pelican nestlings, showing feather papilla^ on body and wings. 



About 1/4 natural size. 



tufts are little pimples or dots, many hundreds of which 

 cover certain parts of the skin. Each of these will event- 

 ually give rise to a perfect feather — quill, vane, barbs, 

 and all. 



The under layer of skin, or dermis, is very thin in 

 birds, much more so than in reptiles and other animals. 



