ORDER ACCIPITRES. 149 



like that under a tooth. The dry and slender pellicle of the 

 interior of this tube is at first a gross fleshy canal, receiving 

 vessels filled with lymph, and very multifariously ramified in 

 young birds. These lymphatico-sanguine fluids serve for the 

 nutriment of the feather. Its barbs are at first nothing but a 

 sort of pap, and are rolled cornet-wise, under long membra- 

 nous tubes. This sort of case for the growing feather, which is 

 analogous to the laminae of the bud which envelopes the grow- 

 ing leaf of the tree, soon drops off in plates. The feather, like 

 the leaf, is more rapidly developed than the other parts, and 

 the nutriment is carried to it in superabundance, from the 

 necessity of clothing the bird. 



When the feather has received its full complement of size 

 and nutriment, it ends, like eveiy other living substance, by 

 drying up. Its saturated canals can admit no further aliment, 

 and it becomes a dead part. It must, therefore, fall ; at the 

 same time the nourishment supplied by the body of the animal 

 is carried to the germs of feathers yet in embryo, under the 

 epidermis, and thus a new plumage succeeds to the old. 



The habitat of birds is not circumscribed within such narrow 

 limits as that of quadrupeds, because, by means of their wings, 

 they can traverse more space, and even cross the seas. The 

 aquatic birds, by alternate flying and swimming, can proceed to 

 the most remote countries. Nevertheless, each species adopts 

 a country, chooses a climate suitable to its nature, and, when 

 the change of seasons obliges it to seek, under new skies, a 

 country analogous to its former one, it is but for a season. 

 These birds always return to their favourite country at the 

 season of reproduction. The stork, indeed, has two separate 

 broods, one brought forth in Europe, and the other in Egyj^t. 



Birds, generally speaking, appear to belong more to the 

 air than to the earth. They constitute moving republics, which 

 traverse the atmosphere at stated periods, in large bodies. 

 These bodies perform their aerial evolutions like an army, 

 crowd into close column, form into triangle, extend in line of 



