CHAPTER YI. 
ABOUT A BIRD’S UNDERWEAR. 
Ir is just possible that underwear is a late acqui- 
sition with the birds as it has been with man, although 
there are some indications pointing otherwise. If 
feathers are moditied scales, it seems scarcely prob- 
able that they were at first so soft and plumous as 
the present downs are, and yet the strong barbed and 
hooked flight quills and external body feathers which 
we see now are evidently of later development. 
Underwear now with the bird is the first consid- 
eration, and the swaddling clothes of all little birds 
form the beginnings or the germs of all subsequent 
plumage. In the same sockets in which the nestling 
downs grow, the larger feathers grow and push out 
their tiny predecessors upon their tips, making the 
little bird really wear, for a little while, his slight 
under garment as an overcoat. So likewise those 
downs which are found among the plumage of adult 
birds, and which, differing strongly from the swad- 
dling down, form a bird’s true underwear, also push 
the nestling downs out. 
These adult downs may be degenerate feathers, or 
they may be very primitive ones, we can not say ; but 
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