The Descent of Man

in 'Ibis,' 1863, p. 33. On Gallus bankiva, Blyth,
in 'Annals and Mag. of Natural History,' vol. i.
1848, p. 455; see, also, on this subject, my 'Variation
of Animals under Domestication,' vol. i.
p. 236.)
The common drake (Anas boschas), after the
breeding-season, is well known to lose his male
plumage for a period of three months, during
which time he assumes that of the female. The
male pin-tail duck (Anas acuta) loses his plumage
for the shorter period of six weeks or two
months; and Montagu remarks that "this double
moult within so short a time is a most extraordinary
circumstance, that seems to bid
defiance to all human reasoning." But the believer
in the gradual modification of species will
be far from feeling surprise at finding gradations
of all kinds. If the male pin-tail were to
acquire his new plumage within a still shorter
period, the new male feathers would almost
necessarily be mingled with the old, and both