Besides the stomach, most birds have a membranous sac, capable of
considerable distension; it is usually called a crop, (by the scientific
_Ingluvies_,) into which the food first descends after being swallowed.
This bag is very conspicuous in the granivorous tribes immediately after
eating. Its chief use seems to be to soften the food before it is
admitted into the gizzard. In _young fowls_ it becomes sometimes
preternaturally distended, while the bird pines for want of nourishment.
This is produced by something in the crop, such as straw, or other
obstructing matter, which prevents the descent of the food into the
gizzard. In such a case, a longitudinal incision may be made in the crop,
its contents removed, and, the incision being sewed up, the fowl will, in
general, do well.
Another curious fact relative to this subject was stated by Mr. Brookes,
when lecturing on birds at the _Zoological Society_, May 1827. He had an
eagle, which was at liberty in his garden; happening to lay two dead rats,
which had been poisoned, under a pewter basin, to which the eagle could
have access, but who nevertheless did not see him place the rats under it,
he was surprised to see, some time afterwards, the crop of the bird
considerably distended; and finding the rats abstracted from beneath the
basin, he concluded that the eagle had devoured them. Fearing the
consequences, he lost no time in opening the crop, took out the rats, and
sewed up the incision; the eagle did well and is now alive. A proof this
of the acuteness of smell in the eagle, and also of the facility and
safety with which, even in grown birds, the operation of opening the crop
may be performed.--_Jennings's Ornithologia_.
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