398 



MANUAL OF HISTOLOGY. 



stated that with this process there takes place, farther, a growth downwards 



of the follicle into the cutis, but this view is combated by other observers. 



This mode of explaining the regeneration of the hair from the old 



papilla, from what we and others 

 have seen, is, we consider, quite 

 correct. Whether it includes all 

 that occurs at the time of change, 

 is another question. 



According to Stiedas state- 

 ments, on the other hand, the 

 papillse of those hairs which are 

 ..ft about to be cast off degenerate. 

 A residue of those indifferent 

 formative cells, however, from 

 which, as we have seen, the 

 specific tissue of the hair is formed 

 ( 214), remains behind in the 

 fundus of the follicle, commences 

 then to grow downwards into the 

 cutis, and becomes cupped by 

 pressing down upon a new papilla 

 rising and formed from the latter. 

 From this cellular mass covering 

 the papilla the new hair takes its 

 origin. 



That the whole structure fol- 

 licle, outer root-sheath, and hair 

 may be newly formed under 

 normal conditions, at a later 

 period of life, appears probable ; 

 indeed, Wertheim believes such an occurrence to be the rule in the 

 change of hair in the human being. This requires, however, more care- 

 ful investigation. 



Pathological neoplasis of hairs and follicles, on the other hand, does 

 occur without doubt under the most extraordinary circumstances. Hairs 

 are met with on mucous membranes, but only extremely rarely ; again, 

 on the internal surface of follicular tumours or cysts in the skin and 

 ovaries, in which case the wall of the cyst has been found to have 

 assumed a similar constitution to the outer skin, and to contain not 

 only hair and sebaceous glands, but also sweat glands. Transplantation 

 of hairs, together with their follicles, succeeds likewise. 



Search among the follicles often brings us into contact with hairs 

 destined to fall out. These have parted from the papilla upon which 

 young cells and pigmentary matters are to be seen. The appearance of 

 their roots is also altered; they seem as though broken up into fibres 

 resembling in figure the end of a broom, and are, like the whole hair, 

 paler and free of pigment. Beneath these the root-sheaths and follicles 

 are narrowed for a greater or less distance, and in the latter small newly- 

 formed hairs may be met with, 



219. 



The tissues we have been engaged in describing up to the present, are 

 combined in various ways, and under great variety of outward form, to 



Fig. 396. From the eyelid of a child of a year old, 

 showing new formation of hairs at the bottom of the 

 sacs. A, early, , later stage of development, a, 

 external, g, internal root-sheath; d, bulb, and , 

 shaft of the old hair; i, sebaceous follicles; k, 

 ducts of sweat-glands; c, funnel-shaped pit at 

 base of the new rudimentary hair which is 

 seen at m, fig. A, to be still quite homogeneous; 

 whilst in fig. B the bulb /, stem 6, and point h, 

 may be recognised. 



