208 MICROBES AXD HEALTH. 



usually grow more rapidly than carcinomas by reason 

 of their more direct blood-supply; and when removed 

 they are more likely to recur, because, as just explained, 

 the malignant cells are more liable to be distributed 

 through the system and may develop at any point. 



Eating cancer, or rodent ulcer, occurs on the face 

 and springs from a sweat-gland, sebaceous gland, or 

 hair-follicle. 



Birth-marks are sometimes called angioma, meaning 

 blood-tumor. They are caused by dilation of the blood- 

 vessels which lie just beneath the surface. 



These different varieties differ only in the size and 

 shape of the cells of which they are formed, and the 

 part of the body in which they are located. Eeally it 

 is a distinction without a difference, for unless success- 

 fully removed all, except birth-marks, are destructive 

 to life. 



Benign tumors, or those not destructive to life, are 

 common connective tissue overgrowths. Usually their 

 only danger is their mechanical interference with the 

 surrounding structures. However, they may rotate at 

 the point where they are attached (pedicle), and this 

 may cause pressure and check the return circulation. 

 The veins would become congested, rupture, and be 

 followed by hemorrhage. Inflammation and suppur- 

 ation may follow, or inflammatory adhesions might oc- 

 cur, the tumor becoming attached to the surrounding 

 structures. This might cause perforation into the di- 

 gestive tract, and be followed by death. 



Their pressure may cause inflammation of the kid- 

 neys, constipation, spasms or paralysis by pressure upon 



