INTRODUCTION. 
XVU 
the Sparrow, the Chaffinch, the Wagtail, the Rook, the Nuthatch, the 
Water Ouzel, and most of the Sparrow tribes, they are so extremely small, 
as to be incapable of performing any material service, or containing any 
quantity of excrementitious matter ; and in the smaller kinds in general, 
they appear like two little excrescences, or bladders. The intestinal canal, 
arbitrarily divided by anatomists into several parts, is in some birds 
extremely short, and with few windings, as in the Nuthatch, the Water 
Ouzel, and Heron, which, in the gallinaceous, carnivorous, and Pie and 
Sparrow kinds, makes many convolutions : and it differs not less in size, 
than in length, in various species of birds. In the Rook it is exceedingly 
large, in the Osprey slender to an extreme degree. The reason of the 
length, or shortness of its convolutions, is evident; if the food of the animal 
be readily digested, and easily yields the life-feeding chyle, the passage 
from its entrance to its emission is short ; but on the other hand, if the 
food require a longer period, for maceration and preparation, it passes 
through an extended course. The duodenum, or upper part of the intes- 
tines, so called in the human subject on account of its being in length about 
twelve fingers’ breadth, is almost contiguous to the oesophagus, or gullet, 
and takes its rise close by the place at which the oesophagus enters ; and 
though intended for the emission of the contents of the gizzard, it is seated 
at its upper extremity, and is larger at its commencement than its termina- 
tion. Contiguous as it is to the oesophagus, the food cannot pass from 
that tube into the duodenum on its entrance into the stomach, because the 
pressure of the gullet, in the act of admission, closes the orifice of the 
duodenum. And, on the other hand, the food, when comminuted and fit 
accipitrine genus, In -which they serve as receptacles for excrementitious matter, they contain but a 
trivial portion; and unless any one conceives that the small quantity which they can contain, 
there undergoes the process of becoming again nutritious to a wonderful degree, and then 
ascending back again through the intestinal canal to the absorbing vessels, he cannot presume, 
that this quantity of foeces can promote the growth of the bird. Even Monro, in his description 
of the anatomy of a Kestrel, strangely asserts that carnivorous birds have no coeca. 
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