232 SPECIAL HISTOLOGY. 



epidermis everywhere dilated to 0'02 — O06"', with saccular 

 diverticula, ofteu lying many together one behind another, of 

 0*04 — 012'", and quite full of sebaceous matter. Here and 

 there a hair was found in one of these ducts, so that it appeared 

 at the same time, to be a hair-sac. 



In investigating the sebaceous glands, they should either be 

 prepared from within, by cutting them with the hair-sacs which 

 belong to them from the cutis, or perpendicular sections, not 

 too fine, may be made. The minuter structure may be best 

 studied, at first in the glands of the scrotum and penis, or labia 

 minora, as these can be isolated without any trouble ; to which 

 end acetic acid, whicb renders the surrounding parts trans- 

 parent, is very serviceable. With the others, so far as form, 

 position, and size, are concerned, the use of alkalies, especially 

 of caustic soda, is most advisable, inasmuch as they clear all 

 the other parts, while they act but little on the glands on 

 account of the quantity of fat they contain. If it be desired to 

 study, not so much the investments, as the cells of the glands, 

 obtaining at the same time a view of their whole figure, there is 

 no plan better than maceration: the hairs with their root-sheaths, 

 and the cellular masses of the sebaceous glands, epithelium 

 and contents, majr then be drawn out altogether. Where the 

 epidermis is thin (on the scrotum, labia majora, glans penis), 

 the same end may be attained in a short time by the dropping 

 on it concentrated acetic acid, and also by using caustic soda 

 in the same manner, though with greater destruction of the 

 glandular cells. To study development, the maceration of 

 fcetal skin, and the rendering it transparent by acetic acid, are 

 of great use. The fat-cells in the interior of the glands are 

 isolated with great ease by teasing out a large gland, and 

 the secretion may be examined without addition, and also 

 with water and caustic soda. 



Literature. — Compare the works cited above under the 

 head of ' Skin/ by Gurlt, p. 409 ; Krause, p. 126 ; G. Simon, 

 p. 9; Valentin, p. 758; the 'Essay on the Hairs' by Esclmcht, 

 which has been mentioned; then the general works by Henle, 

 p. 899 ; Todd and Bowman, p. 424, fig. 92 ; Hassall (pi. liv 

 should be liii), p. 401 • Bruns, p. 349 ; Gerber, p. 75, figs. 40, 

 42, 43, 44, 45, 239 ; Arnold, part II, the figures of Wagner, 

 'Icon. Phys./ tab. xvi, fig. 11, c ; Arnold, 'Icon. Anatom.,' 



