96 NAILS. [SECT. 50. 



The bed of the nail presents upon its surface peculiar ridges, 



Fig. 41. 



Transverse section through the body and bed of the nail; magnified eight times, a. Bed 

 of the nail, with its ridges (black) ; 6. corium of the lateral parts of the wall of the nail ; c. 

 stratum Malphigii of the same part; d. stratum Malpighii of the nail, with its ridges (white) ; 

 e. horn)' layer on the wall of the nail ; /. horny layer of the nail, or proper nail substance, 

 with shallow notches upon its under surface. 



similar to those on the palm of the hand. They begin at the 

 bottom of the fold of the nail, at the posterior edge of its bed, 

 and run forwards partly straight, partly in gentle curves, pro- 

 ceeding from the middle almost as from a pole. At a distance of 

 2V" to 3 1'" from their origin, they are converted into true 

 lamhiw, of o , 024" / to o*i'" in depth, which run straight for- 

 ward, almost to the anterior border of the bed of the nail, and 

 then terminate, as if truncated. The boundary between the ridges 

 and laminae has the form of a curved line, with the convexity 

 directed forwards, and divides the bed of the nail into two seg- 

 ments, which differ both in colour and size. The posterior smaller 

 section is, in its greater part, covered by the wall of the nail, 

 is paler in colour, and supports the root of the nail, while the an- 

 terior larger portion is coloured red, and covered by its body. The 

 ridges and lamina? of the bed of the nail, the number of which 

 varies between 50 and 90, are often beset at their edges with pa- 

 pillae of 0008" to 016'". The wall of the nail has no ridges upon 

 its inferior surface, and but seldom, here and there, a papilla. 

 The papillae begin again at its margin, where they are tolerably 

 long, and pass thence to its upper surface, which differs in nothing 

 from the rest of the cutis on the back of the fingers and toes. 



The corium of the wall and of the bed of the nail is dense, and 

 contains in its deeper portions very little fat, while the ridges and 

 laminae, with their papillae, are rich in fine elastic fibres. The 

 vessels are especially numerous in the anterior segment of the bed 

 of the nail ; posteriorly, in the part lying under the root of the 

 nail, and in the wall, they are more sparingly distributed ; their 

 capillaries (croo5"' to (yoo8'") are met with at the edges of the 

 laminae They also pass into the papillae at the places where these 

 are more developed, and form single loops. The nerves in the 

 deeper portions are arranged in the same manner as those in the 



