FEATHERS OF PENGUINS. 
5 
The degenerate features are found in the vane. Only a very narrow area on each 
side of the shaft presents to the naked eye the characteristic appearance of a continuous 
vane, this central portion being fringed on each side by a wide downy border, while the 
tip of the feather is formed largely by long, flattened 
rami devoid of radii, and produced by a splitting up of 
' the free end of the rhachis to form a series of rods, 
arranged fanwise (fig. 2). By wear the length of these 
rami is greatly reduced, and thus the shape of the feather 
just before the moult differs somewhat considerably from 
that which it originally bore. Partly by this wearing 
away of the rami, and partly by the death of the 
pigment contained therein, the colour change noticeable 
between the feather of a moulting and a newly feathered 
bird is due. 
The Microscopic Structure of the rami and radii. 
That the vane of the contour feathers of the pen- 
guins represents a degenerate, degraded form of that 
characteristic of carinate birds which possess full powers of 
flight, is obvious. That is to say, the feathers of the 
penguin can in no sense be held to represent a primitive 
type of feather, but are unmistakably degenerate struc- 
tures, bearing evidence to an earlier structural perfection 
identical with that which obtains to-day among birds 
that fly. In their degenerate characters they resemble 
the feathers of the flightless Paleeognathee (Ratitze). 
While among the feathers of birds that fly the rami 
of the remiges and rectrices grow shorter as they reach 
the tip of the shaft or main axis of the feather, so that 
none project beyond it, in the penguins the rami of 
what, possibly, answer to remiges show no such curtail- 
ment, but, on the contrary, are of great length, and give 
the shaft the appearance of breaking up distally into a 
fan-shaped series of rami (fig. 2), thereby agreeing with 
the contour feathers. 
The radii are less degenerate than in Struthio, for 
FIG. 2.—THREE FIGURES OF ONE OF 
THE SMALL FEATHERS FROM THE 
PRE-AXIAL BORDER OF THE WING, 
ENLARGED RESPECTIVELY 2, 15, 
AND 20 pDiaMETERS. The most 
highly-magnified figure includes 
only the tip of the feather, and 
shows the fan-like termination of 
the rhachis. 
example, among the flightless birds ; inasmuch as those of the distal series still possess 
their hooklets, though these are reduced both in number and size; they arise, 
however, as delicate, filamentous, curved processes from broad laminee, twisted so as to 
lie with their flat surface upwards, as in functional remiges. 
The radii of the proximal 
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