A History 
of Birds. 
(in) 
THE BIRD WORLD. 
for the fact that they break up when touched into 
a fine powder, which when rubbed between the 
fingers gives an indescribably smooth feeling. It 
is the pow T der from these remarkable feathers 
which gives the peculiar bloom to the beaks of 
many Parrots, as well as to the plumage. As 
to the real purpose of the powder, however, we 
know nothing. 
Structure of a Feather. 
This brief survey of feathers would not be 
complete without a few words as to structural 
characters. 
In the typical feather, say, a quill-feather, two 
main parts are to be distinguished—the stem, 
and the broad flexible blade known as the vane, 
or vexillum (fig. i, v.) The stem may further be 
divided into the quill or calamus (c)—the hollow 
part below the vane—and the shaft or rhachis, 
which is square in section and filled with a white 
pith. The vane runs along on either side of the 
rhachis in the form of a series of tapering, flat¬ 
tened rods, the “ barbs.” They are set so closely 
together that they must be carefully sought for. 
They give to the vane that finely-grooved appear¬ 
ance, or rather the appearance of a series of fine 
lines running obliquely outwards from the shaft. 
If an attempt be made to pull these apart it will 
be found that some considerable force must be 
used, and this is owing to the fact that they are 
locked together by a second series of flattened 
rods, known as barbules, so small as to require 
the miscroscope to reveal them. But the 
mechanism by which this vane is held together 
is so wonderful that I venture to ask my readers 
to bear with me while I endeavour to explain it. 
Mechanism of Interlocking. 
In the diagram of a feather (fig. i), depicting 
the different parts, you will notice on the right 
side, shown as if seen through a magnifying 
glass, the appearance of two barbs and their 
barbules ; while in fig. 3 you will see what 
a section looks like when taken across the barbs, 
parallel with the main axis, in the direction shown 
by the arrow in fig. 1, and seen from the cut 
ends. This figure, of course, is drawn from a very 
highly magnified section. You will now see that 
each barb bears two quite different kinds of bar¬ 
bules, set so that while one series is cut across 
the other remains uninjured. The reason for this 
will appear presently. The uncut series in this 
diagram are those "known as the anterior bar¬ 
bules, because all point towards the top of the 
feather. Each takes the form of a ribbon-like 
plate set slantwise into the barb (fig. 3), and 
having half its length deeply cut, as with a fret¬ 
saw, to form a number of very delicate, almost 
thread-like pieces, the upper short and bearded, 
the under terminating in little hooks (fig. 4). The 
portion bearing these hooklets is twisted in the 
broad ribbon-shaped portion, so as to take a 
vertical instead of a slanting position. The 
series of barbules which run along the other side 
of the ramus or “ barb ” are known as the pos¬ 
terior barbules, and differ entirely in shape from 
those of the anterior series just described. Like 
the anterior series, however, they may be described 
as ribbon-shaped, but they are curled so that the 
lower edge touches the lower segment of the curve 
next in front of it, thus forming a series of 
troughs, as in fig. 6, where they are seen in sec¬ 
tion. The upper edge of each of these curved 
plates, you will notice, is turned over scroll- 
fashion, and further, as in fig. 5, it will be seen 
that the end of the plate is bent upon itself and 
notched. 
How a Feather Holds Together. 
Now, when in position, the bent ends of the 
posterior series are stowed away under a sort of 
roof, formed by the slanting, ribbon-like over¬ 
lapping bases of the anterior series; while the 
hooklets of the anterior series are thrust down 
into the troughs formed by the posterior series, 
and further, so that they catch hold of the scrolled 
edges of the posterior series as in fig. 6 and 6a. 
Now these scrolls, or troughs, are kept apart by a 
very wonderful yet simple contrivance, the series 
of “ teeth,” or notches, near the end of the upper 
edge of each barbule—but for these the edges 
would rub together and cut off the hooklets. In 
some birds of powerful flight a strengthening 
band runs along from the lower edge of the barb 
to the lower edge of that next behind it (fig. 6). 
This serves to keep the barbs in position during 
the strain of flight. Thus, then, this marvellous 
interlocking is the reason why it is so difficult 
to pull the barbs of a feather apart. In the vane 
of a Crane’s quill, in a piece of web fifteen inches 
long, no less than 650 of these barbs were 
counted, each of which bore about 600 pairs of 
barbules—that is about 800,000 for the inner web 
alone, and more than a million for the whole 
feather, and all these are necessary to hold the 
vane together. 
This system of interlocking is most perfect in 
the wing and tail quills. In some feathers, such 
as have a loose, hairy texture, as in the body 
feathers of many birds, these hooklets are but 
feebly, if at all developed. The loose feathers of 
the Ostrich-tribe also lack them, but here they 
were once all much better developed; when the 
birds ceased to fly the feathers degenerated and 
the interlocking arrangement was lost. 
What are known as semiplumous feathers are 
degenerate feathers. 
Structure of the Down, etc. 
Down feathers differ considerably from “con¬ 
tour ” feathers in structure, having little or no 
shaft, all the barbs arising from a common base. 
These barbs are, further, very long, and have 
only very minute barbules. In the Ducks and 
some other birds these barbules take the form of 
triangular nodules, while in other birds, again, 
they are knot-like. 
