286 ELEMENTS OF HISTOLOGY, [chap, xxxiv. 



and the inner root-sheath are formed. As growth 

 and multiplication proceed at the hair-bulb, so the 

 new hair, with its distal-pointed end, gradually reaches 

 the outer surface. It does not at once penetrate the 

 epidermis, but remains growing and burrowing its 

 way for some time in the stratum corneum of the 

 epidermis in a more or less horizontal direction. 



389. In many mammals occur, amongst ordinary 

 hairs, special large hairs, with huge hair-follicles 

 planted deeply into the subcutaneous tissue ; such 

 are the big hairs in the skin about the lips of the mouth 

 in the dog, cat, rabbit, guinea-pig, mouse and rat, <fec. 

 These are the tactile hairs. Their hair-follicle pos- 

 sesses a thick hair-sac, in which are contained large 

 sinuses intercommunicating with one another and 

 with the blood system ; these sinuses are separated by 

 trabeculse of non-striped muscular tissue, and repre- 

 sent, therefore, a cavernous tissue. The papilla is 

 very huge, and so is the outer root-sheath and the 

 hair-root in all its parts. There are vast numbers of 

 nerve-fibres, distributed and terminating amongst the 

 cells of the outer root-sheath (Arnstein). 



390. With each hair-follicle is connected one or 

 two sebaceous follicles. These consist of several flask- 

 shaped or oblong alveoli, joining into a common short 

 duct opening into the hair-follicle near the surface 

 i.e., that part called the neck of the hair-follicle. 



The alveoli have a limiting membrana propria; 

 next to this is a layer of small polyhedral, granular- 

 looking, epithelial cells, each with a spherical or oval 

 nucleus ; next to this, and filling the entire space of 

 the alveolus, are large polyhedral cells, each with a 

 spherical nucleus \ the cell- substance is filled with 

 minute oil-globules, between which is left a sort of 

 honeycombed reticulated stroma. The cells nearer to 

 the centre of the alveolus are the largest. To- 

 wards the duct they become shrivelled up into an 



