OF THE (i LANDS OF THE SKIN. 231 



hair. In fact, I met with very beautiful sebaceous glands, 

 with a considerable amount of sebaceous matter, in the walls 

 of the cyst containing hair, mentioned above, from the lung 

 (Mohr's case); Von Biirensprung has, he believes, though rarely, 

 observed a new development 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. Hypertrophy of the sebaceous 

 glands takes place, according to E. H. Weber (Meckel's 

 'Archiv,' 1827, p. 207), in cutaneous cancer; according to Von 

 Biirensprung 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. 331), 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 car, 

 the areola, and the scrotum. They arise, -either in consequence 

 of the obstruction of the apertures of the hair-sacs by impu- 

 rities, 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 cholesteriu and the 

 Acarus foUiculorum. Milium consists of small white spots on 

 the eyelids, the root of the nose, the scrotum, and ear, which are 

 formed, as Von Biirensprung is certainly right in supposing, from 

 the sebaceous glands also, by their distension alone, without the 

 hair-sacs; in consequence of which, rounded prominences with- 

 out 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 regarded as colossal hair-sacs with sebaceous glands. 

 Further details may be found in the works cited. 



With respect to a little parasite, the Acarus foUiculorum, 

 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 Ichthyosis congenita above referred to, Dr. 11. Miiller and I 

 found the excretory ducts of the sebaceous glands in the 



