OF THE HAIRS. 175 



to be sometimes the expression of the composition of the 

 hairs by the above-described fibre-cells ; in other words, 

 to be the boundary lines of the separate elements of the 

 cortex, and sometimes I consider them to be their nuclei. 

 For, even in the shaft of the hair, the cortical plates all 

 contain fusiform nuclei 001—0016'" long, 00005'"— 0-0012'" 

 broad, which may, in fact, be isolated by rubbing down 

 white hairs which have been boiled in caustic soda. Besides 

 these, there appear in the cortical substance, and with 

 especial distinctness in a whitish place immediately above 

 the bulb, certain fine strise, which are produced by inequalities 

 in the surface of the cortical plates and which do not 

 readily disappear, even after the continued action of alkalies, 

 but eventually give place to a finely fibrous appearance; they 

 cannot be isolated, but are visible in those portions of the 

 cortex which have been separated by sulphuric acid and some- 

 times even are very distinct (fig. 06). 



The description of the cortex, which has just been given, 

 holds good especially for the hair- shaft. In the root of the hair, 

 so long as it is still solid and brittle, we find essen- F - 66 

 tially the same conditions ; and it is only in its 

 lower half, where it becomes gradually softer, at first 

 finely fibrous and then granular, that the structure 

 of the cortex undergoes a progressive change. Here, 

 in fact, the above-described plates are less rigid, 

 and take on more and more distinctly the form of 

 elongated cells (fig. 66) of 0020— 0024'" in length, 

 and 0-009 — 0-011'" in breadth, whose cylindrical, 

 straight, or serpentine nuclei of 0-008 — 0-01'", are 

 very easily rendered visible by the action of acetic acid and 

 may also be readily isolated. The soft and shortened plates 

 then pass into elongated, rounded cells, with short nuclei, the 

 fibrous structure becoming more and more obliterated, and 

 these are finally continued without interruption into the 

 elements of the lowest and thickest part of the hair, the bulb. 

 They (fig. 67) are nothing more than round cells of 0-003 — 

 0-006'", which lie closely pressed together; and like the cells 



Fig. 66. Two cells from the cortex of the root of the hair (the finely-striated part 

 of it immediately ahove the root), with distinct nuclei and a striated appearance, 

 x 350. 



