344 TEGUMENTARY ORGANS. 



epidermis begins to come away in places ; and if the embryo 

 be put for twenty-four hours into stronger spirit, it will come 

 away almost entirely. 



For the purpose of separating the epidermis from the 

 ^orium, LOEWY (Arch. f. mik. Anat., xxxvii, 1891, p. 159; 

 Zeit.f. wiss. Mik., viii, 2, 1891, p. 222) recommends macerat- 

 ing for twenty-four to forty-eight hours, at a temperature of 

 about 40 C., in 6 per cent, pyroligueous acid. Acetic acid 

 of ^ per cent. (PHILIPPSON) is also good. 



The elements of hairs and nails may be isolated by pro- 

 longed maceration in 40 per cent, potash solution, or by 

 heating with concentrated sulphuric acid. 



Horny tissues stain well in safranin or gentian violet 

 .(REINKE, Arch.f. mik. Anat., xxx, 1887, p. 183 ; Zeit.f. wiss. 

 Mik., iv, 3, 1887, p. 383). 



647. Tactile Hairs. RANVIER (Traite, p. 914) recommends 

 for the study of the nerve-endings the boiled formic acid and 

 gold-chloride method, 225. A tactile hair having been 

 isolated with its bulb, and its capsule incised, is put for about 

 an hour into the formic acid and gold-chloride mixture, the 

 gold is reduced in slightly acidulated water, hardening is 

 completed in alcohol, and longitudinal and transverse sections 

 are made. For DRASCH'S method see Zeit. f. wiss. Mik., iv, 4, 

 1887, p. 492. 



648. Skin Nerves. WOLTERS (Arch. f. Dermatol. u. Syphilis, 

 1892 ; Zeit. f. wiss. Mik., ix, 3, 1893, p. 360) employs the 

 haematoxylin method, 726, post. 



649. Intra-epidermic Nerve-fibres. May be studied by the 

 gold method. EANVIER (Traite, p. 900) recommends the 

 boiled formic acid and gold-chloride method, 225. 



He also (p. 910) recommends this method for the study of 

 the tactile menisci of the pig's or mole's snout. 



Pieces of skin are impregnated as directed 225, and 

 after reduction are brought into alcohol, which completes the 

 hardening, and stays the further reduction of the gold. 

 Sections are then made. 



For the study of the tactile menisci of the snout, Ranvier 

 also recommends the lemon juice and gold-chloride method, 

 226. 



