HAIR-FOLLICLES. ccxi 



mucous or Malpigliian layer of the epidermis in general, and contains soft 

 growing cells, including pigment in the coloured races, which at the lower 

 part form a much thinner stratum and pass continuously into those of the 

 hair-knob ; the internal layer or inner root-sheath represents the superficial 

 or horny layer of the epidermis according to some authorities ; but others 

 maintain that it is not continuous with that part of the skin, but ceases 

 abruptly a little below the orifices of the sebaceous ducts. When detached 

 from the hair it is found to be covered internally with imbricated down- 

 wardly projecting scales, forming the cuticle of the root-sheath, which is 

 applied to the cortical scaly cuticle of the hair proper, to whose upwardly 

 directed scales it fits like a mould. Its scales, as well as those of the 

 hair-cuticle, pass, at the bottom of the follicle, into the round cells of the 

 hair-knob. Now, after reckoning off this cuticular lining, the inner root- 

 sheath still consists of two layers, which towards the bottom of the follicle 

 become blended into one. The innermost (that next the cuticula) is known 

 as Huxley's layer ; it consists of flattened polygonal nucleated cells, two or 

 even three deep. The outer layer is composed of oblong, somewhat flat- 

 tened cells without nuclei, in which fissures and holes are liable to occur 

 from accidental laceration, so as to give it the aspect of a perforated or 

 fenestrated membrane. At the lower part both layers pass into a single 

 layer of large polygonal nucleated cells without openings between them. 



The soft bulbous enlargement of the root of the hair is attached by its 

 base to the bottom of the follicle, and at the circumference of this attached 

 part it is continuous with the epidermic lining. At the bottom of the follicle 

 it, in fact, takes the place of the epidermis, of which it is a growth or 

 extension, and this part of the follicle is the true matrix of the hair, being, 

 in reality, a part of the corium (though sunk below the general surface), 

 which supplies material for the production of the hair. This productive 

 part of the follicle is, accordingly, remarkably vascular ; in the large 

 tactile hairs on the snout of the seal and some other animals it is raised in 

 form of a conical vascular papilla or pulp, which fits into a corresponding 

 excavation of the hair-root ; and Kolliker states that a vascular eminence of 

 similar structure exists in the hairs generally, both small and large, of man 

 as well as quadrupeds. As the follicle, in short, is a recess of the corium, 

 so the hair-papilla is a cutaneous papilla sunk in the bottom of it. The 

 papilla is described as being commonly of an ovoid shape and attached to 

 the bottom of the follicle by a narrow base, or a sort of pedicle (fig. cxiv., i). 

 Nervous branches of considerable size enter the follicles of the large tactile 

 hairs referred to, but their final distribution has not been traced ; the pain 

 occasioned by pulling the hair seems to indicate that the human hair- 

 follicles are not unprovided with nerves. 



Fine muscles, each formed of a slender bundle of plain muscular tissue, 

 are connected with the hair-follicles (fig. cxvi.). Their mode of attachment 

 is described by Kolliker and Lister to be the following : they arise from, 

 the most superficial part of the corium, and pass down obliquely to be 

 inserted into the outside of the follicle below the sebaceous glands. They 

 are placed on the side to which the hair slopes, so that their action in 

 elevating the hair is evident. Some anatomists have also recently described 

 a layer of circularly disposed muscular cells as applied immediately to the 

 outside of the follicle. 



Growth of hair. On the surface of the papilla or vascular matrix, at the 

 bottom of the follicle, there is a growth of nucleated cells. The cells for the 

 most part lengthen out and unite into the flattened fibres which compose 



