326 



PRACTICAL HISTOLOGY. 



[XXIX. 



THE NAILS. 



The body of tlie nail rests on the nail-bed, the root of the nail 

 on the matrix, and the part at the root and sides from which the 

 nail springs is the nail-groove. The body of the nail is made up of 

 numerous clear horny cells, each containing a rod-shaped nucleus. 

 The nails are really the stratum lucidum, the stratum corneum 

 being absent, and this rests on the Malpighian layer like that of 



the epidermis. The 

 corium or nail-bed, on 

 which the nail rests, 

 is beset with very 

 vascular longitudinal 

 ridges, papillae being 

 absent. 



Harden the nail of 

 a child and its sub- 

 jacent bed in alcohol. 

 Make T. and L. sec- 

 tions. Stain in hse- 

 matoxylin (balsam) or 

 picro - carmine (Far- 



FlG. 312. T.S. Through Half the Nail. Injected, a. Nail *.<-' a onln+irm\ 

 substance; b. More open layer of cells; c. Stratum rail A? S 

 Malpighii; d. Transverse sections of ridges; e. Nail- 15. T.S. Nail (L 



projecting over the nail; and H). Observe the 

 substance of the nail 

 (fig. 312), and under it a series of transverse sections of the ridges 

 of the corium of the nail-bed projecting into the epidermis. Under 

 this the dense fibrous matrix. 



16. L.S. Nail. Observe the same general arrangement, but note 

 that no papilla-like sections of ridges are to be seen. 



ADDITIONAL EXERCISES. 



17. Elastic Fibres in the Skin. (i.) Those resist gastric digestion ; hence, 

 add some pepsin to .2 per cent, of hydrochloric acid. If small pieces of skin 

 he partially digested in artificial gastric juice at 4OC., part of the connective 

 tissue is dissolved and the elastic networks remain. 



(ii.) Herxheimer's Method. 



(1.) Harden in Miiller's fluid. 

 (2.) Stain 3-5 minutes in 



Hfematoxylin. i grnm. 



Absolute alcohol ... 20 cc. 



Water . . . 20 ,, 



Sat. sol. lithic carb. . i , 



