106 



lodged in the groove between the matrix and the semilunar fold of 

 skin projecting from the dorsum of the finger, is seen covered by a 

 thin layer of cuticle, which extends backwards as far as its posterior 

 border, which is generally jagged and uneven, and forwards upon its 

 dorsum. This portion of cuticle is immediately continuous with that 

 overhanging the root of the nail, and although it is not inseparably 

 blended with its horny substance, yet it is sufficiently adherent to be 

 carried forward with it during its growth, and to remain intimately 

 attached to its dorsal surface until it is worn off by friction or some 

 other mechanical cause. The palmar surface, near to its free border, 

 is also seen covered by cuticle, which in like manner divides into two 

 parts, the one becoming continuous with the cuticle covering the end 

 of the finger; the other passing backwards along the palmar surface of 

 the nail as far as the lunula, where it imperceptibly terminates. This 

 portion of cuticle gradually diminishes in thickness as it extends 

 backwards, and is more intimately connected with the horny part 

 of the nail than was the cuticle on its dorsal surface. Between these 

 layers of cuticle the proper or horny matter of the nail can be distin- 

 guished, presenting fine, nearly parallel, and generally semi-elliptical 

 lines, with their concavity looking in different directions in different 

 parts of the same section, and also a multitude of darkish-looking 

 corpuscles, when viewed by transmitted light, of various forms and 

 sizes. These compose the substance of the horn of the nail, and the 

 lines are the cut edges of the laminae of which it is made up. The 

 horny part of the nail does not increase in thickness after it has ex- 

 tended beyond the lunula, the apparent increase of the nail anterior 

 to this point being derived from the cuticle formed upon the anterior 

 part of the matrix. 



The Matrix of the Nail. 



A mere inspection, even in the living subject, of the parts situated 

 beneath the nail, is, in consequence of its transparency, sufficient to 

 give a general idea of the relative vascularity of the various parts of 

 its matrix. The upper part of the matrix is seen to present a pale, 

 semilunar space, called the lunula. The greater part of the lunula is 

 concealed by the semilunar fold of integument which projects over it; 

 but extending a little below this fold, the lower portion of the lunula 

 is visible, presenting a curved border, with its convexity looking 

 downwards. Immediately below the lunula, and circumscribing its 

 inferior limit, the matrix has a reddish colour, which gradually be- 



