APPENDIX. 543 



limit, the matrix has a reddish colour, which gradually becomes fainter 

 towards the free margin of the nail, but which deepens considerably 

 where the nail becomes detached from the integument. 



" When the matrix is fully injected and the nail removed, the part 

 corresponding to the lunula presents several rows of convoluted capil- 

 laries : the individual convolutions have different degrees of complexity, 

 from a simple loop a little twisted round itself, to a complex tuft of 

 vessels. These rows have their direction from above to below, they are 

 all slightly curved, being concave towards the median line of each nail, 

 and the most external ones are nearly parallel with its lateral margins. 

 These, being the vessels which secrete the horny part of the nail, may 

 be called the horn-vessels. Superiorly these vessels are separated from 

 the rich plexus on the fold of integument which overhangs the nail, by 

 a fibrous and almost non-vascular groove, in which the free border of the 

 nail was lodged, and where the cuticle covering its root terminates. A 

 few vessels, however, pass across this groove from the horn-vessels to the 

 plexus just mentioned, Inferiorly the horn-vessels communicate with 

 quite a different arrangement of capillaries, which run in a more 

 straight course, and are much more crowded together than the horn- 

 vessels. These vessels run nearly parallel with one another, in a direc- 

 tion from behind forwards, and being very near together, render this the 

 most vascular part of the matrix ; and produce that redness immediately 

 below the lunula upon which the form and degree of distinctness of its 

 lower border is dependent. Just below these vessels the surface of the 

 matrix begins to be raised into numerous plications or folds, passing 

 directly forwards, and increasing in depth as they approach the free 

 extremity of the nail, where they become continuous with the raised 

 lines observable on the ends of the fingers. These plicae consist each of 

 a fold of basement membrane, enclosing a series of loops of vessels. At 

 first these loops are small and simple, but they become larger and more 

 complex, as they advance towards the end of the finger, where they are 

 continued from the ridges of the matrix of the nail into those of the 

 skin of the finger, in which they are generally very complex. When the 

 nails are in situ, these ridges are received into corresponding grooves in 

 their inferior surface. Near the part of the matrix where the plicaa 

 commence, several distinct circular or oval openings are sometimes seen 

 passing for some depth beyond the surface, and appearing like follicles 

 or lacunae. These are frequently closed by the opposition of the adja- 

 cent plicae, and thus their presence is rendered doubtful, but they can be 

 seen very distinctly either when some of the material which they contain 

 has been recently removed, or still remains within them in the form of 

 whitish, globular masses. The situation of these lacuna?, where the open- 

 ings themselves are not apparent, can be distinguished by the plexus of 

 capillaries in their vicinity, in the areolae of which their openings are 

 situated." 



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