156 



SPECIAL HISTOLOGY. 



covered ; its somewhat sharp thin edges are hidden in the 

 lateral parts of the fold, and its under surface reposes upon 



Fig. 60. 



the anterior segment of the bed of the nail : lastly, the free 

 edge (m) is, in cut nails, directed straight forwards, but if un- 

 cut, it curves downwards round the ball of the finger, and with 

 the rest of the nail, attains to a length of as much as two inches. 



The lower surface of the body and of the root answer 

 in their form exactly to the bed of the nail, and we there- 

 fore find laminae and ridges upon them, as well as furrows, in 

 the same order as on the latter, only here the edges of 

 the laminse are straight and not papillated, whilst the furrows, 

 instead of having an even bottom, as in the nail-bed, are pro- 

 vided with shallow pits for the reception of the papilla?. By 

 the mutual inter-locking of the elevations and depressions, the 

 intimate union of the nail with the corium is effected, which 

 becomes still more close by the application of the under 

 surface of the wall of the nail upon its base and edges. 



The colour of the nail, so long as it remains in its natural 

 condition, is whitish and transparent, at its free edges ; reddish 

 in the body, with the exception of a very narrow clear 

 margin close behind the commencement of the free edge; in 

 the lunula, whitish ; the colour of the last two portions arising 

 principally from the corium and its blood-vessels which shine 

 through them. Separated from the corium and epidermis, the 



Fig. 60. Longitudinal section through the middle of the nail and bed of the nail, 

 x 8 : a, bed of the nail, and cutis of the back and points of the fingers ; b, mucous 

 layer of the points of the fingers ; c, of the nail ; d, of the bottom of the fold of the 

 nail ; e, of the back of the finger ; /, horny layer of the points of the fingers ; g, be- 

 ginning of them under the edge of the nail ; h, horny layer of the back of the 

 fingers ; i, ends of it upon the upper surface of the root of the nail ; *, body ; /, root ; 

 m, free edge of the proper substance of the nail. 



