A History 
of Birds. 
THE BIRD WORLD. 
(I2l) 
A History of Birds. 
By W. P. PYCRAFT, A.L.S., F.Z.S., Etc. 
{Continued from p. 112). 
How Feathers Grow. 
As touching the growth of feathers, but little 
can be profitably said here. The earliest traces 
of feathers must be sought for in the embryo, 
where the first rudiments of the coming nestling 
down appear in the form of tiny bead-like bodies, 
which soon sink down into a pit. Next an outer 
protecting sheath is developed, and within this 
the mass of pulp which it contains proceeds to 
form first the main axis, and next the barbs and 
barbules. What will prove the tip of the feather 
is the first to be formed, and as this forces its 
way up the lower parts are added, till at hatch¬ 
ing time the whole of the down-feather is com¬ 
pleted. 
At the base of this down-feather lies the germ 
of the contour-feather which is to follow. As 
this grows the down-feather is thrust out upon 
the tip of the new contour-feather, and here it 
may be attached for a very considerable time, 
as in the case of young Herons, for example. On 
its first appearance, as everybody knows, the new 
feather is ensheathed in a thin, delicate blue 
wrapper, the first-formed portion of the vane 
bursting its way through while the lower¬ 
most feather is yet forming. This lower por¬ 
tion is filled with a mass of jelly-like pulp, richly 
supolied with blood. After the feather has com¬ 
pleted its growth, if the barrel or “ quill ” of the 
feather be cut with a sharp knife, the supply 
cases or “06115” which held the pulp will be 
found lying one above another in the centre of 
the quill. 
The Process of Moulting. 
In most birds the feathers are renewed at 
least once annually by the process known as 
moulting—a critical time in a bird’s life. When 
there is lack of .suitable nourishment, or when 
the bird is low in vigour at the moulting season, 
the feathers become curiously indented with fine 
grooves known as “hunger-marks.” 
The annual moult takes place generally after 
the breeding-season; but some birds moult again 
in the spring, when a new and more resplendent 
livery is put on, as in the case of many of the 
Plover tribe. But the quills in such cases are 
not renewed. In some birds, as in the drake 
of the common Wild Duck, a dull livery, re¬ 
sembling that of his mate, is put on—the so- 
called “ Eclipse ” dress, and this i,s worn for some 
weeks. By the middle of August the new and 
characteristic “ breeding ” dress is well in evidence 
and by October is completed. This “ Eclipse ” 
dress, then, answers to the dull dress put on after 
the breeding season by the Plovers, and is 
simply moulted again in a month or two instead 
of being worn till the following spring. 
How Colour-change is Effected. 
While some birds put on a new and brightly- 
coloured dress in the spring, others brighten up 
their plumage quite as conspicuously by simply 
shedding the tips of the feathers assumed at the 
autumn moult. No better instance of this can 
be found than that of the Linnet, which, by 
this shedding process, gains the beautiful, rich 
brown back, and rose-pink breast, that make 
these birds so much prized. From some as yet 
unexplained reason, however, captive birds, if 
taken in July, before the autumn moult, develop 
yellow in the place of red, which colour is 
never regained : if taken in the autumn, the red 
breast appears in the following spring, but never 
again. The beautiful plumage of the Starling 
is similarly attained by this method of shedding 
the outer edges of the feathers, and the Chaf¬ 
finch gains its blue head in the spring by this 
same process. 
Whether birds can gain an access of colour 
to the feathers without a moult is still a disputed 
point. Some hold that there can be no doubt 
about the matter, while others, apparently as 
well qualified to speak on the subject, deny the 
possibility of such a change, absolutely. Per¬ 
haps some of my readers may be able to throw 
some light on this subject. 
Colour-feeding Among Savages. 
That the colour of feathers can be influenced 
by feeding is a fact too well known to the readers 
of The Bird World to need further comment, 
but it may be interesting to remark that this 
fact is well known to the savage people of 
Brazil, who feed a species of green Parrot on the 
fat of Siluroid fishes, the feathers as a conse¬ 
quence becoming beautifully variegated with red 
and yellow. Another race of South Americans 
change the colours of Parrots by plucking out 
such feathers as they propose shall be altered, 
and inoculating the spot from which the feather 
was taken with the milky juice obtained from 
certain glands of a small toad. The new 
feathers now appear of a brilliant yellow colour, 
and on being plucked out, it is said, grow again 
of the same colour without any fresh inoculation. 
