EPITHELIAL TUMORS. 335 



as gelatine or mucus. Their color depends, as a rule, oo their 

 vascular condition, and any blood extravasations which may have 

 occurred also produce certain alterations, so that on section a sar- 

 coma may appear white, yellow, brown, gray, dark red, and even 

 entirely black (melanotic sarcoma). 



The metamorphoses which occur in the sarcoma are of some diag- 

 nostic value, especially the mucous softening, which leads to the 

 formation of cysts, and sometimes to bony deposits. This is fre- 

 quently noticed in sarcoma, and the ulceration in sarcoma of the 

 skin and mucous membranes occurs without producing any active 

 disintegration of the tumor. 



There are very rare forms of osteosarcoma, or myeloid tumors, 

 which occur in the marrow cavity of bones. They have been 

 noticed in the forearm, also in the shoulder-blade, the bone of 

 the arm, and femur (Siedamgrotzky and others). Circumscribed 

 nodules are developed in the medullary cavity which gradually 

 crowd out the bone by their growth, and, when new bone is formed 

 from the periosteum, filling up the entire cavity. In this manner 

 we find enormous lumps, or masses, possessing the hardness and 

 firmness of bone, and in the centre is found a soft tumor sur- 

 rounded by a bony cyst. Sooner or later the soft parts penetrate 

 the bony envelope and certain of the fluid escapes. 



The treatment of sarcoma consists in removing, as soon as 

 possible, the esntire tumor; a small portion allowed to remain may 

 form a nidus for the commencement of a new growth. We see 

 occasionally, a group of tumors of the connective tissue, called 

 angioma. These are mostly in the form of fibro-angioma, small, 

 ball-like, tough, cutaneous tumors, generally bluish-black on sec- 

 tion. 



Infective genital tumors will be found under Diseases of True 

 Infection. 



Epithelial Tumors. 



Papilloma. Papilloma originates by hyperplasia of the cover- 

 ing epithelioma of the cutaneous and mucous membrane, with a 

 proportionate formation of connective tissue. These are separated 

 as follows : 



(a) Warts. A wart is a neoformation of the papillae of the skin 

 and of the epidermis. VYarts vary very much in size, from a 

 lentil to the size of a pea. The external covering of a wart is very 



