lOG CLASS AVES. 



Accident must frequently cause the separation of the laminae, 

 and though their natural elasticity, aided by the hooked bristles, 

 will soon restore them to their contiguity necessary for flight, 

 still the bird is enabled, by an oily secretion, with which it 

 charges its bill, to anoint and adjust the delicate apparatus of 

 the laminae, by drawing the vanes of the feather gently through 

 the bill. Birds of passage are generally observed to do this care- 

 fully, previous to starting on their protracted periodical flights. 



This very short sketch of the feather of a bird destined to its 

 locomotion, may be aided by the figures inserted of the struc- 

 ture of these feathers, as displayed to us by the microscope. 



The feathers already shortly described are those calculated 

 for the locomotion by flight of the bird. There are others 

 fitted only for its clothing, which are of a very different con- 

 struction, though not less curiously adapted to their intended 

 purposes. These are set in a quincunx form over the whole 

 body, thus, : • : . Immediately upon the skin is a covering, 

 called down, composed of delicate plumes, of different sizes, 

 and of extreme softness and pliability, flaccid, branching, and 

 scattered. Instead of a shaft, beset with parallel laminae, 

 readily adhering or separating, the shaft of the down is fur- 

 nished with rays which ivill not unite. Nor do they lie toge- 

 ther, but are scattered in all directions, and furnished with 

 knots, similar to those on a bamboo-cane, and applied closely 

 to the skin, thus forming a general covering to the body, so 

 essential to preserve and equalize the vital heat in all situa- 

 tions. To prevent the consequences of so light a substance as 

 the down being blown about, a provision is made for confining 

 it. This is done by the next tier of feathers, which is of a two- 

 fold structure, on the upper side partaldng of the laminous 

 formation of the flying feather, while the under side is lined 

 with down, which, uniting with that immediately next the skin, 

 confines it to its place, composing altogether a regularly spread 

 under garment, thus braced, as it were, and wrapped round 

 the body. Next to these compound feathers, which thus com- 



