vI FORM AND FUNCTION 159 
young Partridge has quill feathers big enough to 
enable him to fly, to some extent, very soon after 
leaving the egg. These are shed and replaced several 
times during his first summer and autumn, thus keep- 
ing pace with his rapid growth. Thrushes, Blackbirds, 
and Fieldfares have one complete moult in their first 
autumn. 
Change of Colour without Moulting. 
In spring the cock Gray Linnet becomes the “ Red 
Linnet,” and appears with a crown and breast of 
crimson in place of the dull gray of winter, and 
yet it is certain that no feathers are shed. In cap- 
tivity he gradually loses his crimson splendours, which 
fade to ochre-yellow. After the first moult he assumes 
and retains the dull plumage of the hen. The fore- 
head of the Redpoll becomes blood-red and _ his throat 
and breast carmine, equally without the shedding of 
a feather. The nape and back of the Brambling turn 
from reddish-brown striped with black to pure glossy 
blue-black without any moult ; and, to take one more 
instance, the Blackheaded Gull, in the course of a 
fortnight, dyes the white plumage of his head black, or, 
more strictly speaking, a very dark brown. In some 
cases the explanation is perfectly simple ; the crown 
and breast feathers of the Linnet have wide gray 
borders which in spring break off and let the crimson 
that was before covered up become visible. The same 
is the case with the Redpoll, Brambling, the Snow 
Bunting, whose back plumage becomes black in spring, 
and the Blue Throat. In some of these cases Gatke 
