158 SPECIAL HISTOLOGY. 



papillae, or in thin portions of the skin (prepuce, glans, eyelids, conjunc- 

 tiva bulbi) after the addition of acetic acid and dilute solution of caustic 

 soda, or according to Gerber's and Krause's method. Gerber boils the 

 skin until it is transparent, lays it a few hours in oil of turpentine until 

 the nerves are white and glistening, and then examines them in fine 

 perpendicular sections made with the double knife. According to 

 Krause, the nerves are seen very well after treating the skin with nitric 

 acid, if the right amount of action is hit upon. The elastic tissue of the 

 skin comes out well under the action of acetic acid, soda, and potassa. 

 The smooth muscles may be readily isolated in the tunica dartos with 

 more difficulty in the penis and in the areola, where it needs familiarity 

 with them, in order in all cases, to recognize them with the naked eye. 

 On the hair-sacs they are rendered visible microscopically, if a sac, with 

 the sebaceous glands which appertain to it, be isolated, especially after 

 the application of acetic acid, as small bundles near and in front of the 

 sebaceous glands, but best and very easily in perpendicular sections of 

 boiled skin (Henle). The examination of the fat-cells is especially in- 

 structive in thin persons, in whom their membranes and nuclei are 

 readily visible: in other cases their membranes are readily demonstrable 

 by the aid of ether, which extracts the fat ; but the nuclei are seen with 

 difficulty, though they may occasionally be discovered here and there 

 even in full cells. The epidermis must, for its Malpighian layer espe- 

 cially, be examined fresh, in fine perpendicular sections, to which acetic 

 acid and dilute solution of soda may be added ; the horny layer, par- 

 ticularly by the addition of alkalies, in perpendicular and horizontal 

 sections ; however, mere maceration in water separates its elements from 

 one another, and those who are practised can discover them in fresh 

 preparations, when viewed both laterally and from the surface. 



Literature. Gurlt, " Vergleichende Unters. liber die Haut des Men- 

 schen u. d. Haus-saugethiere," c., in Mull. " Archiv," 1835, p. 899 

 (good figures for the period) ; Raschkow, " Meletemata circa Mammal, 

 dentium evolutionem," Vratisl, 1835 (first more complete description 

 of the elements of the epidermis under Purkinje's guidance) ; Simon, 

 "Ueber die Structur der Warzen u. iiber Pigmentbildung in der Haut," 

 Mull. "Arch.," 1840, p. 167 (pigment-cells in the rete of white persons) ; 

 Krause, article "Haut," in Wagner's " Handworterbuch," II. 1844, p. 

 127 (a detailed and excellent treatise); Kolliker, "Zur Entwicklungs- 

 geschichte der aussern Haut," in " Zeitschrift f iir wiss. Zool.," Bd. II. 

 p. 67 ; " Histological Observations," ibid. II. p. 118 ; Eylandt, " De 

 musculis organicis in cute humana obviis," Dorp. Liv., 1850. Besides 

 these refer particularly to the works of Simon (" Die Hautkrankheiten 

 durch anatomische Untersuchungen erlautert," 2 Aufll., Berl., 1851); 

 Von Barensprung (" Beitrage zur Anat. u. Pathol. der menschlichen 



