STRUCTURE OF BIRDS. 79 



being largest on the belly, may be best seen there ; they exist, 

 however, in the other parts of the body, but are not readily dis- 

 tinguishable from the down-feathers, properly so called. If it 

 be necessary to give these feathers a name, they may be called 

 flahe-featliers. 



In most birds, after the feathers have been removed, we 

 find a sort of envelope, consisting of hairs as it were, set so 

 widely, and so small in themselves, that they might readily be 

 overlooked. These are the hairs that are singed off in a fowl 

 after it has been plucked. In the Pheasant their structure is as 

 follows : — from a very short bulbiform tube rises a very slender 

 roundish piliform shaft, resembling a hair of the human head, 

 but much smaller, and straight, which, at the extremity, gives 

 off two or three short simple barbs on either side. This is the 

 most simple modification of the feather, if we except the quill 

 of the Cassowary. 



In all nestling birds, before they have received their full 

 plumage, the skin is covered w^ith a greater or less quantity of 

 down, resembling that described above as occurring in adult 

 birds. This down is generally more or less developed, even 

 before exclusion from the q^^^. It consists of two orders of 

 plumules. One set, which is connected solely with the skin, 

 is similar in structure and relations to the down of the adult 

 bird, each plumule consisting of a tube, out of w^hich issues a 

 pencil of filament, furnished with filamentules. The other set, 

 which, at first sight, is not distinguished from the former, being 

 blended with it, is of the following nature. The plumules at 

 first arise from the skin in the ordinary manner and form, but 

 having fewer filaments than the others. Shortly after, w^hen 

 the feathers begin to sprout, they are observed to be elevated 

 from the skin, being borne upon the tips of the feathers. The 

 tips of the extreme barbs of the feathers are drawn together, 

 and united into a point by a scaly envelope, similar to that 

 which encloses the feather itself during the first stages of its 

 growth. From this point there proceeds a pencil of filaments, 

 consisting of a variable, but generally small, number. These 

 filaments have tw^o lateral series of filamentules, and are loose 

 and floating, and more or less spirally twisted. The filaments 



