116 NATURAL HISTORY. 
some peculiarities in the digestive organs, most birds hav- 
ing, in place of the process of mastication, a crop to soak 
their food and a gizzard to grind it. 
197. Feathers have some resemblance to hairs, but dif- 
fer from them in some important respects. A feather 
has commonly three distinct parts: a horny tube, or quill 
part; a stem proceeding from this tube; and lamine, 
which are commonly joined together by barbs or teeth 
on their edges. The laminz thus locked together enable 
the feather to press upon the air in flight. In what is 
called down the laminz are very narrow, and are entire- 
ly separate. 
198. The wing may be considered as a hand with a 
feathery appendage, so that it may press upon consider- 
able air at once, and thus raise up the bird. According- 
ly, we find that the bones of the wing are essentially the 
same as those in the arm 
and hand of man. In Fig. 
96 we have the bones of a 
bird’s wing. Comparing 
this with the correspond- 
ing part of the skeleton 
of man in Fig. 1, we have, 
ty the ate ae II., the 
the bones of the eae cane 
ce, the bones gates one 
ing to those in the body 
of the hand; 0, the thumb- 
bone; 1, 2, 3, 4, attempts 
at fingers. These rudi- 
mentary fingers, you see, 
are very different from the 
fingers in the wing of a 
Bat, Fig. 20. There they 
Fig. 96.—Bones of Gyrfaleon’s Wing. needed to belong as frame- 
! = a _— 
See 
—— 
en 
