Dermoid Cysts. 417 



of a nut to tliat of a fist, is rounded and liUcd with a hunch of 

 tang-led hair and a (hrt\ l)ro\vn fluid consisting of secretion fnjui 

 the sweat-glands, fat and desquamated epithelial cells. The wall 

 of the sac. which may be easily shelled out of its bed, is thin, quite 

 like the iibrous structure of the cutis, and lined on the inside 

 with cpiderm and attached hairs, loosened hairs occurring in the 

 contents as free bunches. .Microscopically the wall has all the 

 appearances of the cutaneous structure. These dermoid cysts are 

 met particularly in the region of the neck and jaw, generally 

 developing in these situations from tissue derived from the 

 branchial arches (braj!chi(\Q:ciioiis cysts) ; they are also met about 

 the shoulder or elbows, in which cases they may be referred to 

 faults in the development of the anterior liml) bud (Leisering. 

 Johne. Grams and others), in the umbilical region, and in the 

 testicles and ovaries. 



As earlv as 1854 Remak explained the origin of dermoid cysts 

 bv conceiving an al)normal development of the arches and resultant 

 enclosure of a bit of the germinal epidermal layer as their basis ; 

 and it mav also be possible that injuries caused to the skin in the 

 region of fissures may give rise to them, provided the borders of 

 the fissures become the seat of a cicatrizing proliferation and. 

 further, provided the base of the skin fissure becomes isolated and 

 brought to lie underneath the scar. 



The dermoid cysts of birds contain feathers ( fcalhcr-folliclc 

 cysts, cxstonia pcuuifcruni ) and are found from the size of an egg 

 to that of a fist within the abdominal cavity of geese. UK^re rarelv in 

 ducks and chickens. The cyst, surrounded by a thick layer of fat, 

 is sometimes free in the ])eritoneum or may l)e attached by a peri- 

 toneal fold to the ovary and lumbar region. The number of feath- 

 ers (the plume not unfolded because wet with fluid) may reach 

 several hundred. 



Analogous to tlie dermoid cyst but not growing in cystic form, and 

 appearing as protruding islands of hairy skin, are the dermoid fcratoinata 

 of the cornea (also of palpcbra tcrtia). which are met comparatively com- 

 monly in cattle and dogs. They are congenital anomalies and originate 

 from a misplacement or transplantation in the formation of the palpebral 

 fissure. 



In the same way as from the epidcrm and cutis cystic foci ma_\- 

 arise from separation or misplacement of their cells, epithelial 

 lined cysts may also develop from the mucous membrane 

 tubules and glandular ducts in embryonic life from budding or 

 other anomalies of development, particularly from "rests" of 



