THE NAILS. 



249 



the intersaccular partitions in ovarian tumors, and in those of the 

 testis. 1 



5. Some of the peculiar appearances of the tongue in disease are 

 due to changes in its epithelial cells. They may even become a 

 nidus for the development of parasitic vegetation ; of which the pe- 

 culiar white coat produced by the oidium albicans (Fig. 155) in some 

 cases of diphtheritis, is an illustration. 



Fig. 156. 



SECTION II. 

 THE NAILS. 



Nails are merely a modification of the epidermis, being histolo- 

 gically a very much condensed compound scaly epithelium. (Fig. 

 156.) They are also, by maceration, 

 detached in continuity with it. And, 

 according to Mulder's investigations, 

 they differ from epidermis in chemi- 

 cal compositioD, only in containing a 

 larger proportion of sulphur and car- 

 bon. 



The surface covered by the nail, 

 and upon which it is developed, *is 

 called the led of the nail. A trans- 

 verse section of it, and of the nail 

 also, is seen in Fig. 157. It presents 

 a series of peculiar ridges on its sur- 

 face, beginning under the root of the 

 nail, and at first radiating outwards 

 from the centre for a distance of 2J 

 to 3J lines; whence they become pa- 

 rallel and more prominent, and take 



Transverse section of nail and its matrix. 

 A. Skin. B. Stratum Malpighii of nail. c. 

 Horny layer of same. a. Papillae of nail- 

 matrix. 6. Cells of the Malpighian stra- 

 tum, c. Ridges of horny substance of nail. 

 d. Deepest layer of perpendicular cells of 

 Malpighian layer, e. Upper layer of flat- 

 tened cells of the same. /. Nuclei of the 

 true nail substance. 



Body and bed of nail, transverse section, a. Bed of nail, with its ridges. &. Corium of lateral 

 portion of wall of the nail. c. Stratum Malpighii, with its ridges (white), d. Papilla, e. Cuticle of 

 wall of the nail. /. Horny layer of nail, with short notches on its under surface. Magnified S 

 diameters. (KUlliJcer.) 



1 London Lancet, Sept. 1856. 



