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Facsimile
Transcription
developed in the pelican. They are furnished
with muscles with which the air may be
expelled by compression. These continuous air
recepticals [receptacles]are extensions from the lungs and
serve several pup [purposes]among which are:
1. Respiration
2. They mechanically aid respiration in
the fixed lungs by compression and
released compression upon them.
3. They lessen the birds specific gravity.
4. By inflation of the air cavities beneath
the wings of some large birds (e.g.
Wood ibis), these birds can sore [soar] for
long continued periods and the
necessary muscular excertion [exertion] to keep
the wings our stretched are greatly lessened
5. They contribute to sustain the song of
birds and to give it tone and strength
(boom of prairie chickens and sage
chickens).
The trachea is subject to dilation
and contraction in any part of its
length. The most remarkible [remarkable]
expansion of the lower part of the
tube occur in many sea ducks
and mergansers; several lower
rings being enormously enlarged
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