14 



THE ANIMALS AND MAN 



and the horny covering of bill and feet are simply modified 

 portions of the skin. Of what uses are the feathers to the 

 bird? 



The feathers are of several kinds or types, each of which 

 has a name. In the wings and tail are long, stiff feathers 

 called quill feathers; those which overlie the whole body 

 and bear the color pattern are called contour feathers; the 

 small soft ones which cover the body more or less com- 

 pletely (being, however, mostly hidden by the contour 

 feathers) are called down feathers or plumules, while, 

 finally, the scattered, slender, soft, or stiff hair-like ones, 



with thin bare stem and small 

 terminal tuft of branches, 

 are called thread feathers 

 or filoplumes. 



Pull a quill feather from 

 the wing and examine it in 

 detail. Note the central stem 

 or shaft, composed of two 

 parts, a basal hollow trans- 

 parent quill, which bears no 

 web and by which the feath- 

 er is inserted in the skin, and 

 a longer terminal four-sided 

 part, the rachis, which bears 

 on either side a web or vane. 

 Examine the vane with a 

 lens and see that it is composed of many nairow linear plates 

 called barbs, and that each barb is fringed in turn with smaller 

 branches called barbules. Finally, each barbule bears many 

 fine barbicels or hamules, which can be seen with a micro- 

 scope. The barbs comprising the vanes are interlocked 

 with each other (fig. 6), thus forming a true web and gi\'ing 

 the vanes, composed of small, weak parts, much strength 

 and power of resistance. Rub the feathers from tip to base. 



Fig. 6. Bit of bird's feather, great- 

 ly magnified; s, shaft; b, barb; 

 bl, barbule; h, hamule. 



