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XVIII. — On the Structure and Formation of the Nails of the 

 Fingers and Toes, By G. Rainey, Esq., M.R.C.S., Demon- 

 strator of Anatomy, St. Thomas's Hospital. Communicated 

 by John Qdekett, Esq. 



(Read April 21, 1847). 



The nails being probably too much regarded by physiologists 

 merely as a modification of cuticle, and as resembling it in all their 

 essential characters, have not been either very minutely or clearly 

 described. 



Although these organs are so intimately connected with the skin 

 as very properly to allow of being classed with its appendages, yet 

 being designed to perform a function peculiar to themselves, and dif- 

 ferent to any one performed by the cuticle, it must be admitted that 

 they require an express organization. Also, the vascular surface 

 upon which the nails are formed, their matrix, must require a dispo- 

 sition of blood-vessels different from that of the cutis of other parts, 

 where it is merely covered by the ordinary cuticle. 



The object of this paper is to show that the nails consist of at least 

 two distinct structures : one proper to them, the horny structure, and 

 the other the cuticular one ; and also that their matrix possesses one 

 set of vessels expressly for the secretion of the horny part of the nail, 

 and another set for the formation of the cuticular portion ; and that 

 besides these, there are other vessels differing in their characters and 

 arrangement from the preceding, and probably intended to furnish a 

 material, intermediate in some of its properties between horn and cu- 

 ticle, and destined to blend these together, and thus to preserve their 

 union during the growth and protrusion of the nails. However far 

 this idea may be correct, the anatomical fact of there being these 

 three different arrangements of vessels is indisputable, as may be 

 seen in PI. 22, fig. 1, taken from preparations of the injected matrix 

 of the nail in the cabinet of the Microscopical Society. 



Structure of the Nails. 



If a thin, vertical section be made lengthways through a finger-nail 

 from its posterior to its anterior or free margin, as shown in PI. 22, 

 fig. 2, the external or dorsal surface of that portion of it which was 



