Ml" W. Macgiilivray on the Covering of' Birds, 255 



to an elongated and attenuated stem, laterally giving insertion 

 to a series of connected filaments. A feather of the ordinary 

 kind, or what may be assumed as a perfect feather, consists of 

 the following parts. 



1. The tube or barrel^ (in Latin tubus, in French tube or 

 tuyau), a tubular part, by which it is fixed into the skin. It 

 consists of a thinnish transparent tube, or hollow cylinder, ha- 

 ving the colour and texture of a thin plate of clear horn, and 

 being chemically of the same nature. This tube, which is more 

 or less protracted, being in some feathers scarcely a fortieth part 

 of their length, as in the hypochondrial feathers of Paradisea 

 apoda, while in others it exceeds a third, as in the quill-coverts of 

 the Flamingo, is abruptly narrowed at the lower, or with reference 

 to the connection of the feather with the skin, the proximal end, 

 where it is closed up by a dry membrane, forming part of an 

 apparatus that has been subservient to the growth of the other 

 parts of the feather, and which now, in a dry and shrivelled 

 state, extends along the whole length of the tube, in its interior. 

 This part, when taken out of the tube of the feather, presents 

 the appearance of a very thin transparent membranous tube, di- 

 vided internally by transverse dissepiments. At each of these 

 dissepiments the tube separates on pulling it gently, and each 

 portion so obtained presents the appearance of an inverted fun- 

 nel, the prolonged extremity of which, being continued into that 

 of the next above it, an internal tube is produced, which occu- 

 pies the centre of the membrane. This membrane is, in ordi- 

 nary language, termed the pith, from its resemblance, if not in 

 nature, at least in position, to the pith of a plant. It might, 

 with more propriety, be named the internal membrane of the 

 tube, membrana tubi interior, membrane interieure de la tube. 

 The tube is invested externally with a sort of close sheath, con- 

 •sisting of several layers of condensed cellular membrane. With 

 regard to the texture of the tube itself, it would seem to be com- 

 posed internally, and, in its greatest thickness, of a uniform 

 horny substance, which, in many species, however, shews longi- 

 tudinal fibres, while the outer part, though not to a great depth 

 from the surface, is composed of transverse or annular fibres. 

 Hence the reason why, in making a pen, the slit is always clean- 

 est when the outer layer has been scraped off. The longittidi- 



