12 EXTERNAL PARTS 



3. The downy feather, or plume'- feather, where the stem is 

 short and weak, the rhachis soft, and the barbs have long, 

 slender, thread-like barbules without booklets. These are 

 abundant everywhere over the body of the sparrow, under and 

 among the feathers which form the outer coating. 



4. The hairy^ feathers, where the stem is very long and slen- 

 der and the vanes very small. These can readily be seen after 

 plucking the feathers from the sparrow as, apparently, hairs 

 scattered over the body. They are the parts singed off by 

 the cook before preparing a bird for the oven. 



5. The bristly feathers or bristles," where the rhachis lacks 

 vanes either throughout, or toward, the external end. These 

 are abundant around the mouth of the sparrow. 



Many feathers show in different portions two or even more 

 of the above types. A complete feather may have a downy 

 base, a. x>ennaceous center, and a bristly" tip. 



Location of different kinds of feathers. — The feathers which 

 form the great bulk of the plumage of birds are called contour 

 feathers. These usually consist of a perfect stem or quill at 

 the base, an interlocked or pennaceous tip, and a downy por- 

 tion between. They give outline, color, and most of the orna- 

 mental appendages of birds. Among the different birds there 

 is a wonderful variety of contour feathers. They range from 

 the almost fish-like scales of the penguins to the magnificent 

 gorget of the hummingbirds. In their various modifications 

 they form almost all the gorgeous crests, tufts, ruffs, and 

 plumes which render the birds the most beautiful of animate 

 forms. These contour feathers can all be moved by muscles 

 situated under the skin. Many birds have thousands of these 

 feather muscles, by the aid of which the feathers can be made 

 to stand erect, as can readily be seen in the turkey when its 

 tail is erected and its feathers ruffled up, giving the bird the 

 appearance of great beauty and of twice its usual size. 



Under these contour feathers and usually entirely hidden 

 from view, but forming more or less of a complete covering to 

 the body, there are the downy ' feathers. These have the plume- 



