256 Mr W. Macgillivray wi the Covering of Birds. 



nal fibres are distinctly seen in the quills of the domestic cock, 

 and of the gallinaceae in general. The tube terminates above, 

 that is, distally with respect to the body of the bird, in the next 

 part. 



2. The shaft or stem, (in Latin Eachis, in French La Tige). 

 This is a continuation of the tube, but considerably altered in 

 its forms. It is generally as follows. From being of equal dia- 

 meter with the tube, it gradually diminishes, so as to terminate 

 in a point. Considered in respect to its length, it is more or less 

 curved, the outer, upper, or anterior part, or back, as it may be 

 called, being convex, the inner, under, or posterior part, or face, 

 concave. The back is more or less convex, but generally in a 

 small degree, considered in its transverse section. The face is 

 formed of two convex surfaces, separated by a groove which runs 

 along its whole length, or of two inclined planes meeting at an 

 obtuse angle. The two sides are more or less plane, and gra- 

 dually approximating, as is equally the case with the back and 

 face, from the base toward the tip, where all four meet, and so 

 terminate in a point. Internally the shaft consists of a soft, 

 compact, elastic substance, of a white colour, having much of 

 the mechanical nature of cork, and which might be named the 

 internal suberose substance of the shaft, materia rachis subei'osa 

 interna, la matter e interne liegeuse ds la tige. It is separated 

 longitudinally by a line proceeding from the groove of the face 

 of the shaft, and this division can be traced along its whole ex- 

 tent even to the back, on the external surface of which there is 

 sometimes a corresponding sunk line ; but the two pieces of the 

 corky matter are in close contact along this dividing line, and do 

 not even separate distinctly by tearing them asunder. The ex- 

 ternal part, or horny envelope or case of the shaft, is much thin- 

 ner than the tube, the latter of which is prolonged farther along 

 the back of the shaft, than along its face, although there is no 

 line of distinction between them. Some further explanations, 

 however, are necessary here, before the structure of the shaft 

 can be rightly understood. Where the tube terminates on the 

 face of the feather, and where the groove of the shaft com- 

 mences, the line of union of the dorsal and lateral surface of the 

 shaft meets its fellow of the other side, having gradually left the 

 posterior margin of the shaft, crossed its side obliquely, and be- 



