530 TUMOES. 



ceum, and as milium. In some instances the epithelia are trans- 

 formed into large, shining, sometimes stratified, colloid corpuscles, 

 which were erroneously thought to be the infectious material 

 of the so-called mottuscum contagiosum, when a number of smaller 

 tumors form around a large adenoma. In milium the sebaceous 

 mass is inspissated, and by deposition of lime-salts is trans- 

 formed into cretaceous material. Tumors of this kind are 

 often inclosed by a thick fibrous connective-tissue capsule ; 

 they are liable to become inflamed and ulcerated or to enter the 

 cystic degeneration. 



In mucous membranes, most of the myxomatous sessile or 

 pedunculated so-called polypous tumors are adenomatous (Bill- 

 roth), and deserve the name myxo-adenoma. They occur in the 

 mucosa of the nasal cavities, the throat, the larynx, the tympa- 

 num, the rectum, and the uterus. In children, polypi occur most 

 frequently in the rectum, while in middle-aged persons they are 

 more commonly found in other localities. Their size varies 

 greatly. Those of the rectum sometimes grow to be as large as a 

 chicken's egg 5 those of the uterus reach a still larger size. Ex- 

 ceptionally a marked papillary character is observed on the sur- 

 face. Eectal polypi show a distinct tubular structure in the 

 newly formed glands. Ciliated epithelia occur both on the sur- 

 face of the tumor and in the ducts of the glands, especially in 

 polypi of the nasal, laryngeal, and aural regions. Those of the 

 uterus also exhibit ciliated columnar epithelium, and are found 

 both in the mucosa of the cervical canal and in that of the uterine 

 cavity proper. In the latter situation they are often combined 

 with the lymphoid variety of myxomatous connective tissue, re- 

 presenting a benign type of tumors, though sometimes occupying 

 quite extensive tracts of the mucosa. 



A larger number of medullary elements in the myxomatous 

 connective tissue indicates a more rapid growth and greater 

 proneriess to recurrence after extirpation. Exceptionally a trans- 

 formation into myeloma and cancer takes place, particularly after 

 repeated attempts at eradication. 



In the female breast, adenoma of the acinous variety is also 

 of common occurrence, combined with myxoma or fibroma. 

 Sometimes the tumor is circumscribed and sharply defined from 

 the surrounding tissue ; at other times the growth invades one 

 or both mammary glands almost uniformly, which results in the 

 formation of very bulky tumors. If the connective tissue is pro- 

 fusely provided with medullary elements, the growth becomes 



