BIRDS IN GENERAL. 



453 



the grosser parts of the faeces. In passing 

 through the ureters, it resembles milk curdled 

 or lightly condensed ; and, being cast forth, 

 easily congeals into a chalky crust." 



From this simple conformation of the ani- 

 mal, it should seem that birds are subject to 

 few diseases ; and, in fact, they have but few. 

 There is one, however, which they are sub- 

 ject to, from which quadrupeds are, in a great 

 measure, exempt; this is the annual moulting 

 which they suffer ; for all birds whatsoever 

 obtain a new covering of feathers once a year, 

 and cast the old. During the moulting season, 

 they ever appear disordered; those most re- 

 markable for their courage, then lose all their 

 fierceness ; and such as are of a weakly con- 

 stitution, often expire under this natural ope- 

 ration. No feedingcan maintain their strength; 

 they all cease to breed at this season ; that 

 nourishment which goes to the production of 

 the young is wholly absorbed by the demand 

 required for supplying the nascent plumage. 



This moultiug-time, however, may be 

 artificially accelerated ; and those who have 

 the management of singing-birds frequently 

 put their secret in practice. They enclose 

 the bird in a dark cage, where they keep it 

 excessively warm, and throw the poor little 

 animal into an artificial fever ; this produces 

 the moult; his old feathers fall before their 

 time, and a new set take place, more brilliant 

 and beautiful than the former. They add, 

 that it mends the bird's singing, and increases 

 its vivacity; but it must not be concealed, that 

 scarcely one bird in three survives the opera- 

 tion. 



The manner in which nature performs this 

 operation of moulting is thus : the quill, or 

 feather, when first protruded from the skin, 

 and come to its full size, grows harder as it 

 grows older,and receivesakind of periosteum 

 or skin round the shaft, by which it seems 

 attached to the animal. In proportion as the 

 quill grows older, its sides, or the bony pen- 

 part, thicken ; but its whole diameter shrinks 



and decreases. Thus, by the thickening 

 of its sides, all nourishment from the body 

 becomes more sparing ; and, by the decrease 

 of its diameter, it becomes more loosely fixed 

 in its socket, till at length it falls out. In the 

 mean time, the rudiments of an incepient quill 

 are beginning below. The skin forms itself 

 into a little bag, which is fed from the body 

 by a small vein and artery, and which every 

 day increases in size till it is protruded. 

 While the one end vegetates into the beard 

 or vane of the feather, that part attached to 

 the skin is still soft, and receives a constant 

 supply of nourishment, which is diffused 

 through the body of the quill by that little 

 light substance which we always find within 

 when we make a pen. This substance, which 

 as yet has received no name that I know of, 

 serves the growing quill as the umbilical ar- 

 tery does an infant in the womb, by supply- 

 ing it with nourishment, arid diffusing that 

 nourishment over the whole frame. When, 

 however, the quill is come to its full growth, 

 and requires no further nourishment, the vein 

 and artery become less and less, till at last 

 the little opening by which they commu- 

 nicated with the quill becomes wholly obli- 

 terated ; and the quill, thus deprived, con- 

 tinues in its socket for some months, till in 

 the end it shrinks, and leaves room for a re- 

 petition of the same process of nature as be- 

 fore. 



The moulting season commonly obtains 

 from the end of summer to the middle of au- 

 tumn. The bird continues to struggle with 

 this malady during the winter; and nature 

 has kindly provided, that when there are the 

 fewest provisions, that then the animal's ap- 

 petite shall be least craving. At the begin- 

 ning of spring, when food begins again to be 

 plentiful, the animal's strength and vigour re- 

 turn. It is then that the abundance of pro- 

 visions, aided by the mildness of the season, 

 incite it to love, and all nature seems teem- 

 ing with life, and disposed to continue it. 

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