99 



it is almost absent in perfectly fresh specimens. Its circular fibrous 

 character, and its epithelial origin is well shown in the rhinoceros. Its 

 thickness is considerable. It is lined interiorly by a delicate epithelium, 

 which often bears the impression of the scale of the hair it is in 

 contact with. At the bulbous termination this epithelium receives a 

 considerable increase in ,*density, and is reflected on to the hair, forming 

 a conspicuous collar. It is precisely at this spot that we find the hair 

 assume its scaly character. We have therefore no hesitation in affirming, 

 that there is strict continuity with the coating of a hair and the ordinary 

 epidermis. In some instances — the hare and pig, for example — the epi- 

 thelium does not appear to extend to the bottom of the sheath, but is 

 reflected on to the hair half-way down. A process, however, of epidermis, 

 is prolonged between the sheath and the hair, as far as the former 

 extends. 



There can be little doubt that this sheath has been correctly con- 

 sidered as a modeller of the hair. In young hairs, the follicles are very 

 simple, consisting merely of an inversion of the epidermis forming the 

 homy sheath, and an outer coating of rete mucosum lying in a depres- 

 sion in the cavity. 



At the bottom of some follicles, a large vesicle may be seen ; it appears 

 to contain an oily material, and to be connected with the bulb of the hair 

 by a small neck. Its walls are of moderate thickness, but of small 

 tenacity. I am quite ignorant of its use, and am inclined to think it 

 somewhat of a monstrosity, its presence is so mre. 



The bulb of the hair is formed at the bottom of the follicle. It may 

 be easily examined, either in situ, or after forcible extraction of a single 

 hair. Two parts are readily detected — ^an outer funnel, and au inner cone ; 

 the former continuous with the hair, the latter with the medulla ; both are 

 formed from the cells of the rete mucosum. In the hair or funnel, the 

 cells are large, with small nuclei and a number of fibres ; and colour 

 granules e.xist in the inter-cellular spaces. In the cone or medulla, the cells 

 are smidl, and the nuclei of remarkable size. What becomes of the cells 

 in the fibrous portion, I am unable to trace, for the collar of the hiiir is 

 always opaque. They probably form the cement by which the fibres are 

 ultimately held together. Kolliker's idea seems to be that they are con- 

 verted into fibres — a view I do not concur in, as the latter are so evidently 

 produced outside the cell walls. 



Grey hairs answer for microscopical examination, better than the bro>vn 

 or black. 



The cells of the inner cone, iiTegularly situated at first with re.spect to 

 each other, gradually arrange themselves as they proceed onwards, forming 

 a broad line — like a column of soldiers, shoulder to shoulder. 



