222 SPECIAL HISTOLOGY. 



The minuter structure may be best studied, at first in the glands of the 

 scrotum and penis, or labia minor a, as these can be isolated without any 

 trouble ; to which end acetic acid, which renders the surrounding parts 

 transparent, is very serviceable. With the others, so far as form, posi- 

 tion, 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, may then be drawn out altogether. Where the epidermis 

 is thin (on the scrotum, labia major a, 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 foetal 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 Eschricht, 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.," 

 Fasc. II., tab. xi., fig. 10, and Berres, tab. xxiv., besides that G. Simon, 

 " Ueber die sogenannten Tyson'schen Dru'sen an der Eichel des mann- 

 lichen Gliedes," in Muller's " Archiv," 1844, p. 1. 



OF THE MUSCULAR SYSTEM. 



76. To this system belong all the transversely striped muscles, 

 which, together with their accessory appendages, the tendons and 

 fasciae, serve for the movements of the skeleton, of the proper organs of 

 sense, and of the integuments. These muscles constitute a system 

 situated between the integuments and the bones, and between the bones 

 themselves, the individual parts of which are so associated and united by 

 common membranes, that they may conveniently be regarded as a whole. 



77. The proper elements of the muscles in question, visible even to 



