Doiti^crous Cysts. 421 



the ovary and testicle [heterotopic odontoteratomata). Gurlt 

 recorded a testicular tumor of a horse, about the size of a fist, 

 of stony hardness, containing six molar teeth (three separate, 

 three merged together), together with thin plates of bone repre- 

 senting a rudimentary alveolar process, and a fibrous capsule; 

 in a second instance the egg-sized tumor contained, besides a 

 single tooth, a lot of hair and a fiuid material made up of a 

 mixture of perspiratory and sebaceous material. 



In addition to the above cysts and dentigerous tumors there 

 occur, especially in the sexual glands of both sexes, a number 

 of other tumors of complex composition, sometimes showing an 

 irregular mixture of heterogeneous tissues of all three embryo- 

 blastic layers, sometimes a definite tissue arrangement repre- 

 senting clearly the structure of a number of organs. Because of 

 their close relation to monsters the collective names teratoma or 

 emhrxoma are used in connection with these peculiar formations, 

 which undoubtedly originate from embryonal cells or tissues 

 which have been segregated and become independent at an early 

 developmental period. 



The external tumors of this type, growing in the superficial 

 tegumental tissue or in the mouth, are possibly the results of 

 partial cleavage from amniotic threads, as it is known that 

 indentation of an embryonic tissue can cause its division and 

 double development; and even transplantation may be effected 

 from injuries caused by amniotic bands. These external tera- 

 tomata usually appear as tumor-like, pedunculated formations, 

 of lobulated outline, and are composed of hairy skin, rudimen- 

 tary jaws with teeth and mucous memlDrane covering, fat tissue, 

 nerves, muscle and glandular structures. (For illustrations and 

 details v. E. Sigl, Monatshcft f. pr. Tierheilknnde, Stuttgart. 

 1902.) The compound teratomata developing in t}ie interior of 

 the body, especially in the ovary and testicle, may sometimes 

 originate from germinal segregations from the primitive seg- 

 ments of the vertebral column or from the indifferent cells of the 

 Wolffian body; or it is possible, as Marchand's theory would 

 make plausible, that they may arise from the separate develop- 

 ment of one segmentation cell. According to the experimental 

 studies of Roux and others each one of the primitive segmenta- 

 tion products of the ovum— that is, each segmentation cell— is 

 capable of producing an entire embryo; thus the possibility 

 arises that an isolated segmentation cell in course of progressive 

 development may form a group of embryonic tissues, which be- 



