152 PATHOLOGY 



giant-celled sarcoma, small and large round-celled 

 sarcoma. 



Lymphosarcoma. Melanosarcoma. 



Alveolar sarcoma. Chloroma. 



Tubular sarcoma. Myxosarcoma. 



Angiosarcoma. Psammoma. 



Sarcomatous cylindroma. Osteosarcoma. 



Adenoma. Adenomata are benign tumors which 

 spring from glands and present a more or less typic 

 glandular structure. Adenomata occur in the skin, 

 mucous membranes, mammary glands, liver, kidneys, 

 and ovaries, wherever glandular tissue exists. While 

 they are essentially benign in their nature, those of 

 certain localities, particularly of the uterus and 

 stomach, are prone to carcinomatous degeneration. 



Carcinoma (Cancer). Carcinomata are malignant 

 epithelial tumors. They always arise from epithelial 

 structures, as the skin, mucous membrane, glands, etc., 

 and, spreading rapidly by infiltration and metastasis, 

 are usually rapidly fatal. They occur most frequently 

 in those past middle age, though no age is exempt from 

 their devastation. Many of the lower animals are sus- 

 ceptible, including rats and mice, and most of the experi- 

 mental work on cancer has been done on rats and mice. 

 It has been determined that in rare instances carcino- 

 mata spontaneously disappear, after which the organism 



