FEATHERS OF BIRDS, 397 



clear idea of the several steps of the process to be described, 

 to advert to the structure of a feather in its fiiiislicd state. 

 For this purpose we need only examine a common feather, 

 such as that represented in Fig. 228, where s is the posterior 

 surface of the solid stem, which, it will be perceived, is 

 divided into two parts by a longitudinal groove, and from 

 either side of which proceed a scries of laminae, composing, 

 with their fibrils, what is termed the vane of the feather 

 (v.) The lines from which these laminsc arise, approach 

 one another at the lower part of the stem, till they meet at 

 a point, where the longitudinal groove terminates, and where 

 there is a small orifice (o,) leading to the interior of the 

 quill. From this part the transparent tubular portion of the 

 quill (t) commences; and at its lower extremity (l) there 

 exists a second, or lower orifice. 



The entire organ which forms the feather, and which may 

 be termed its matrix, is represented in Fig. 229, when it 

 has attained the cylindric form already described; of which 

 A is the apex, or conical part, that rises above the cuticle, 

 and B the base, by which it is attached to the cerium, or true 

 skin. A white line is seen running longitudinally the whole 

 length of the cylinder, and anotlier, exactly similar to it, is ^ 

 met with on the opposite side: the one corresponds in situ- 

 ation to the front, and the otlicr to the back o^the stem of 

 the future feather. On laying open the matrix longitudi- 

 nally, as is shown in Fig. 230, it is found to be composed 

 of a sheath or capsule, and of a central pulpy mass, termed 

 the hulh. The capsule consists of several membranous lay- 

 ers (c, E, s, I,) which are more consolidated near the apex, 

 and become gradually softer and more delicate, as we trace 

 them towards the base of the matrix, where their formation 

 is only beginning to take place. 



The laminre and theiV fibrils, the assemblage of whicli 

 constitutes the vane of the feather, arc tlic parts which arc 

 first formed; and their construction is cflected in the sjiace 

 between the outer capsule (c,) and the centKil bulb (n,) in a 

 mode which is exceedingly remarkable, and dillcrcnt from 



