330 Tumors. 



large growths of the skin or subcutaneous tissue often produce 

 only the most trifling effects. 



In the second place the pathological significance depends 

 upon the degree of special power which the tumor possesses to 

 disseminate through the system. The less a tumor involves 

 strictly the surface of an organ or the less it remains closely 

 confined to its point of origin as a single isolated growth, and 

 the more it sends out oilshoots which extend into the lymph- 

 passages and bloodvessels and thus obtains opportunity for its 

 cells to be loosened and carried into new locations in the body, 

 the more the development of the neoplasm acquires specially 

 dangerous characteristics. The outshoots of a tumor, made up of 

 its proliferating cells, force their way first in the surrounding tis- 

 sue, especially the connective tissue lymph spaces, which repre- 

 sent the beginnings of tlie lymph passages, causing a continually 

 increasing portion of the organ in which the growth occurs to be 

 destroyed by the infiltration (the tumor therefore spoken of as a 

 destructive growth or locally penetrating grozcth). In such new 

 formations the external, visible outlines are usually not its actual 

 limits; the apparently healthy adjacent tissue may conceal the 

 roots of the tumor only to be found microscopically. The sur- 

 geon, whose skill can in many cases aft'ord permanent recovery 

 by removal of the growth, is unable occasionally (for technical 

 reasons or because the precise limits of tht individual roots 

 cannot be recognized by the unaided eye) to remove the entire 

 tumor in the operation performed for its ablation ; from the 

 portions thus left, earlier or later the same tumor may return in 

 the original site or close by (recurrence of tuuior). The tumor 

 cells grow into the- lymph passages, sometimes as continuous 

 cords or roots ; or the cells may become loosened or be carried 

 away by the lymph current or perhaps by leucocytes. The 

 same thing occurs where the roots of the tumor penetrate through 

 the wall of a blood vessel, sometimes developing as long pro- 

 cesses within its lumen ; and particles of the growth may be 

 swept off by the blood current. Under such circumstances, at a 

 shorter or longer distance from the (primary) autoblastoma (the 

 principal tumor) arise secondary tiiinors. daughter tumors or 

 metastatic tumors. The lymphogenous metastases are carried 

 into the immediately adjacent tissues and into the lymphatic 

 glands draining the site of the original growth; the embolic 

 (haematogenous) ones pass into the lungs or the organs of 

 the greater circulation (v. chapter on Embolism). When in this 



