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MANUAL OF HISTOLOGY. 



forward for a short distance on the surface of the nail. This 

 fold of skin is called the nail fold, and the tissue upon which 

 the nail is seated is termed the bed of the nail. That part of 

 the nail imbedded in the flesh posteriorly is the root of the nail, 

 and the remainder its body. The flesh underlying the root 

 the corium is called the matrix, and that underlying the body 

 of the nail the bed of the nail proper. The matrix and bed of 

 the nail proper are separated by a more or less convex line, gen- 

 erally easily seen through the nail and known as the lunula. 

 The bed of the nail is composed of corium and rete Malpighii 

 tissue. There is no fat in its subcutaneous tissue. The rete 

 here dips down between the papillae of the corium as in other 

 parts of the skin. The papillae in the matrix project forward, 

 and are shorter and closer together than in the bed of the nail 



FIG. 124. Transverse section of the nail through the bed of the nail proper : a, nail : 6, loose cor- 

 neous layer beneath it : c, mucous layer : d, transversely divided nail ridces: e. nail-fold without papillae ; 

 /. the horny layer of the nail-fold which has pushed forward on the nail ; <j, papillae of the skin of the 

 finger. 



proper. In this latter structure the papillae also project for- 

 ward (Fig. 124, d] and increase in length as the free margin of 

 the nail is approached. The rete Malpighii covers the papillae 

 of the nail, forming cones, which till the space between the 

 papillae. In the bed of the nail proper the transition from rete 

 cells to horny cells is very rapid, whilst in the matrix it is 

 gradual. Consequently, this portion of the nail is softer than 

 the other. It is from the matrix that the nail is formed, and 

 from the corneous cells of the body of the nail that the nail is 

 made thicker. The soft cells are directed forward and become 

 more horny as they advance. The under surface of the nail- 

 fold covering the posterior part of the nail is provided with 

 epidermis, which is continued forward a short distance on the 

 upper surface of the nail. 



