3668 Birds. 



nous substance, and the remnant of the dried and protruding follicle 

 is apparent, as also the solid pointed tip of the barrel with its aper- 

 ture. The shrivelled follicle contained in the barrel contracts into a 

 variable number of chambers, exceeding twenty, which are sharper at 

 the upper part, where the still recognizable umbilical vessel may be 

 traced to the protruding part of the follicle, more obtuse in the mid- 

 dle, and more numerous at the bottom. The interior of the stem is 

 filled with numerous very small white vesicles, resembling elder-pith, 

 and mostly of an oval shape, extending from the insertion of the folli- 

 cle to the very tip of the feather.' 1 — Malpighi, Opera Posthuma, p. 96. 



Cuvier adds but very little to this statement. He says if the sheath 

 be opened just as it penetrates the skin, it is found to consist of nu- 

 merous cylindrical layers of horny and transparent matter, inclosing a 

 cylinder of gelatinous substance, in which blood-vessels run ; that its 

 top is conical and much harder than the other part, and that it is en- 

 veloped with a layer of black matter, which is the first rudiment of 

 the barbs of the feather, which, when the cylinder bursts the sheath, 

 and is exposed to the air, splits as it dries, and forms the first barbs, 

 and that the stem of the feather elongates and hardens at the same time. 

 More of the cylinder then protrudes, and an additional quantity of 

 barbs and stem are thus produced, until the whole of the vanes and 

 shaft are perfected. After which the barrel or tubular part solidifies 

 and becomes continuous with the shaft, of which it had previously con- 

 tained the germ. — See Cuvier, ' Lemons d'Anatomie Comparee,' iii. 604. 



Should any one feel inclined to investigate this interesting subject 

 farther, let him consult Dutrochet's " Observations sur la Structure et 

 la Regeneration des Plumes, &c," in l Journal de Physique,' lxxxviii. 

 333; Fredk. Cuvier' s "Observations sur la Structure et le Developpe- 

 ment des Plumes," in ' Memoires du Museum,' xiii. 327 ; and, for Al- 

 bert Meckel's views, ' Archiv. fur die Physiologie,' xiii. 37. 



Now from the above quotations it seems clear to me that there is a 

 very close analogy between the human hair and the growing feather: 

 both spring from a follicle, sheath or capsule; in both there is a shaft 

 or stem ; in both there is a barrel ; both are nourished by juices in 

 which the colouring matter is supposed to reside, (though in the case 

 of human hair, no less than in the case of feathers, great difference of 

 opinion seems to exist as to ihe cause of the colour). But there is 

 this great difference between the two as regards the matter in ques- 

 tion, that whilst the human hair is always growing, and is therefore 

 being always nourished by the juices; the feathers, when once per- 

 fectly developed, remain fixed in their sockets in the skin, to which, 



