CHAP. XIV.] 



STRUCTURE OF HAIR, 



419 



ment (fig. 87, c), and gradually to mount on the hair, becoming 

 more compressed against it in their ascent, until they form upon 

 its surface a thin transparent colour- 

 less film, in which the overlapping of 

 the delicate cells is still exhibited by 

 elegant and exceedingly fine sinuous 

 cross lines (fig. 88, d, d'} . The fibrous 

 interior and this peculiar cortex to- 

 gether compose the shaft of the hair. 

 By the continual emergence of fresh 

 portions of the shaft from the follicle, 

 fragments of the cuticular lining of 

 the latter are apt to be drawn up 

 upon the hair, aided, probably, in this, 

 by the imbrication of its surface, and 

 are often found clinging around it for 

 some way ; but they are not to be 

 regarded as any part of the hair itself. 

 In the larger hairs there is usually 



a double Series Of these imbricated . Transverse section of a hair of the head, 



,. -i -i ,- i . ., shewing the exterior cortex, the fibrous tissue 



COl'tlCal SCaleS; the OUter having itS with its scattered pigment, and a central space 



teeth interlocked with those of the mied with piffment *' A similar secti n f 



a hair, at a point where no aggregation of 

 -i , -i -i -i i pigment in the axis exists, c. Longitudinal 



inner, but apparently but loOSely section, without a central cavity, shewing the 



imbrication of the cortex, and the arrange- 

 ment of the pigment in the fibrous part. d. 

 Surface, shewing the sinuous transverse lines 

 formed by the edges of the cortical scales. 

 d'. A portion of the margin, shewing their 

 imbrication. Magn. 150diam. 



adherent to them. This outer series 

 seems to be intermediate between the 

 true cortex and the cuticle of the fol- 

 licle, and to belong rather to the latter, since it does not appear 

 upon the extended portion of the hair. The cortex is much denser 

 than even the fibrous part of the hair, and is less acted upon by 

 strong solution of potass. 



From the preceding description, it will be evident that the fibrous 

 part of the hair is a peculiar development of the cuticular cells 

 resting on the bottom of the follicle, that the imbricated cortex is 

 formed by a single series differently developed at the circumference 

 of these, and that beyond this series comes the cuticular lining of the 

 follicle ; so that the hair is neither covered nor underlaid by cuticle, 

 but it is, in fact, the modified cuticle of the bottom of the follicle. A 

 thin layer of papillary tissue probably coats the bottom of the follicle 

 in most cases ; and where the hairs are large, and especially where 

 they serve principally as tactile organs, there may be a projection of 

 a true papilla, furnished with nerves and capillaries, into the bulb of 

 the hair, as is very conspicuous in the whiskers of some animals and 



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