OF THE GLANDS OF THE SKIN. 221 



the cyst containing hair, mentioned above, from the lung (Mohr's case) ; 

 Von Barensprung has, he believes, though rarely, observed a new de- 

 velopment of sebaceous glands in cicatrices of some years' standing. 

 When the hairs fall out, the sebaceous glands seem to disappear, at 

 least I have repeatedly failed in finding them in bald places. Hyper- 

 trophy* of the sebaceous glands takes place, according to E. H. 

 Weber (Meckel's "Archiv," 1827, p. 207), in cutaneous cancer; ac- 

 cording to Von Barensprung in akrothymion, or moist warts (1. c., 

 p. 81), and in ncevus pilosus. The comedones also, among which I 

 place Lichen pilaris, at least as Simon defines it (1. c., p. 334), 

 are hair-sacs and sebaceous glands distended with sebaceous matter, 

 which are especially frequent where the glands are distinguished by 

 their large size, as on the nose, the lips, the chin, the ear, the areola, 

 and the scrotum. They arise, either in consequence of the obstruc- 

 tion of the apertures of the hair-sacs by impurities, or of the formation 

 of a more viscid and consistent secretion ; and they contain, besides 

 one or many hairs, which may also be wanting, fatty cells, like those of 

 the normal cutaneous sebaceous matter, epidermic cells proceeding from 

 the hair-sacs, free fat, often crystals of cholesterin and the Acarus 

 folliculorum. Milium consists of small white spots on the eyelids, the 

 root of the nose, the scrotum, and ear, which are formed, as Von Baren- 

 sprung is certainly right in supposing, from the sebaceous glands also, 

 by their distension alone, without the hair-sacs; in consequence of 

 which, rounded prominences without any aperture are formed and raise 

 up the skin : their secretion, similar to that of the comedones, may still 

 frequently be pressed out through the hair-sacs. Finally, there can no 

 longer be any doubt that the sebaceous cysts which lie in the corium 

 itself (atheroma, steatoma, meliceris, and molluscum\ must also be re- 

 garded as colossal hair-sacs with sebaceous glands. Further details may 

 be found in the works cited. 



With respect to a little parasite, the Acarus folliculorum^ which 

 resides in healthy and distended hair-sacs and sebaceous glands, I must 

 refer to G. Simon (1. c., p. 287). In the case of Iclithyosis congenita 

 above referred to, Dr. H. Muller and I found the excretory ducts of 

 the sebaceous glands in the epidermis everywhere dilated to 0-02-0-06 

 of a line, with saccular diverticula, often lying many together one 

 behind another, of 0-04-0-12 of a line, 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. 



* [These glands, when hypertrophied, frequently lose their glandular structure, and are 

 changed into yellowish granular masses. DaC.] 



