branches. Should he fall, by some mischance, into the water, 
he promptly swims to the bank; and by the aid of his long 
first finger, and wing-claws, and his huge feet, soon climbs 
back. But the most wonderful part of his story is yet to come. 
So long as these youngsters can only scramble about they 
are in constant jeopardy. A wing-surface at least big enough to 
break the force of a fall is an urgent necessity. And so the 
growth of the quill-feathers is, so to speak, pushed forward with 
all possible speed. But if all the feathers grew at the same 
tate, there would speedily come a time when the outermost 
feathers would make the claw at the end of the finger useless, 
while the wing-surface, as a whole, would be insufficient. To 
obviate this difficulty, the development of the outermost feathers 
is held in abeyance till the inner feathers of the hand, and the 
outermost of the forearm, have grown big enough to suffice to 
breake the force of the fall. As soon as this stage is arrived at, 
_the outermost quills, whose growth has been held in abeyance, 
rapidly develop; the finger decreases in length, and its claw 
disappears, while that of the thumb soon follows suit. And thus 
it comes about that the hand, in the nestling, is relatively much 
longer than in the adult. But in its mid-period it may be taken to 
represent the adult stage of the wing of the ancient Archzopteryx. 
This bird could have been but a poor flier, and probably during 
the time it was moulting its quills it was absolutely flightless, 
119 
