SECT. 58.] 



HAIRS. 



IO7 



of which we shall presently speak. Under certain circumstances, 

 they also possess granular pigment; in other respects, they 



Fig. 4G. 



Plates or fibre-colls of the cortical substance of a hair, treated with acetic acid ; magnified 

 350 times. A. Isolated plates : 1 . from the surface (three single, two united); 2. from the 

 side. B. A bundle composed of many such fibre-cells. 



arc homogeneous, and no finer elements, such as fibrillse, can be 

 observed. They appear to be more intimately united with each 

 other in the longitudinal direction than in the transverse, whence 

 the easy splitting of the cortical substance into the above-men- 

 tioned long fibres. These fibres — which cannot well be designated 

 as compound constituents of the cortical substance, inasmuch as 

 their elements can be isolated, and they themselves are much 

 too irregular — form a compact bundle, without evident lamellae 

 as in the nail and epidermis; and in this way produce the 

 cortical substance, the principal constituent of the hair. The 

 dark spots, dots, and stria of the cortex are of different kinds, and 

 are chiefly, i. granular pigment ; 2. spaces filled with air or liquid ; 

 and 3. nuclei. These spots, as is shown by caustic potass and soda, 

 which soften and swell the cortical substance without acting upon 

 the spots, are, for the most part, nothing but aggregations of pig- 

 ment granules, which are situated in the plates of the hair, and 

 vary very much in their size and form. A second kind of dark 

 spots resemble very much depositions of pigment, but are found to 

 be small cavities filled with air. These cavities are very numerous 



