OF THE NAILS. 101 



parts of the fold, and its under surface reposes upon the anterior segment 

 of the bed of the nail : lastly, the free edge (m) is, in cut nails, directed 



Fig. 60. 



e / 



^^MM0BHS3flHB>_^ 



m 



straight forwards, but if uncut, 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 therefore find laminae and ridges 

 upon them, as well as furrows, in the same order as on the latter, only 

 here the edges of the laminae 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 papillae. By the mutual 

 interlocking 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 color 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 commence- 

 ment of the free edge ; in the lunula, whitish ; the color 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 

 nail is of a tolerably uniform whitish color, and transparent, though 

 somewhat whiter at the root than in the body. 



49. Structure of the Nail. The nail consists in its deeper parts of 

 a soft, somewhat pale stratum mucosum, which is distinguished from the 

 hard external horny layer, or proper nail, still more sharply than in 

 the common epidermis. It covers the whole of the lower surface of the 

 root and body of the nail, frequently also a small part of the upper surface 



FIG. 60. Longitudinal section through the middle of the nail and bed of the nail : 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 ; rf, 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, beginning 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 ; k, body ; Z, root ; m, free edge of the proper substance of the nail. Magnified 8 

 diameters. 



11 



