62



Mr. W. P. Pycraft,



growth of the quills follows a quite peculiar course. The

primaries at the tip of the wing have their growth arrested until

the inner primaries have increased sufficiently to form a

parachute in the case of a fall. So soon as this stage has been

reached the outermost primaries and the secondaries commence

to grow, and within a very short time the claws become

absorbed, and the growth of the fore-arm overtakes and exceeds

that of the hand. The claws and long hand being of no further

use, in short, become suppressed.


In the young Fowl a similar order of growth is followed,

but since flight, in a brood which has exchanged an arboreal

for a terrestrial nursery, is now imperative at the earliest

possible stage, the innermost primaries grow at an exceedingly

rapid rate, so that flight for short distances is possible within a

few hours after birth. Hence the peculiar form of the wingseen

in the plate fig. 2. The free-finger-tip—though minus the claw

-—is here very conspicuous. Save as an adaptation in a precocious

nestling to a sometime arboreal nursery, the free-finger-tip is

inexplicable.


But the young game-birds possess another curious feature.

In them the first flight feathers of the forearm are formed by

the major coverts. Later these are replaced by the secondaries.

Now it may be remembered, I pointed out that while the secon¬

daries of the young Touracou were yet partly ensheathed in their

embryonic coverings (page 57) the major coverts had com¬

pleted their growth. Fiom this, and the form of the wing

generally, I venture to prophesy that when we get earlier stages

in the development of the Touracou we shall find the same

features are produced which obtain in the young Opisthocomus,

and that the first flight feathers of the forearm will be the major

coverts, which, later, will be found to be replaced by the secon¬

daries. I have the more confidence in this since Mrs. Johnstone

has specially remarked, in her most interesting paper, that the

young bird, very early in life, “ used to scramble about on its

basket lid.” But she does not however, say, whether the wings

were used in this scrambling. Possibly, now that attention is

drawn to the matter she may be able to enlighten us on this

point.



