170 GROWTH 



the body as a whole and from that of the differentiation of its 

 parts. At the present time such growths are viewed as cellular 

 perversions. They are masses of cells and tissues, or combina- 

 tions of tissues arranged in abnormal fashion and developed in 

 abnormal amount. They do not serve the normal functions of 

 the body and are in the end more or less destructive to the life 

 of other normal tissues. The growth of tumors in general is 

 progressive, rapid, and may be destructive to the host. They 

 infiltrate into parts of the body otherwise normal, and in the 

 very process of their growth interfere with the nutrition and 

 growth of normal parts. 



Abnormal growths of pathological type have been classified 

 on many bases. Perhaps the most satisfactory is the grouping 

 according to the type of tissue from which they have been de- 

 rived and which they resemble. Almost every tissue in the body 

 may give rise to tumor growths. The supporting tissues of bone, 

 cartilage, connective tissue, lipoid tissue, lymphatic, blood vas- 

 cular, all may give rise to special growths. These are called osteo- 

 mas, chondromas, fibromas, lipomas, angiomas, etc. Or, per- 

 verted growths may develop from muscles — either smooth 

 muscle or striated, from nervous tissues — either ganglionic, sup- 

 porting, or of epithelial type, or they may be derived from 

 gland, or pavement epithelium, or epidermis. 



Certain of these perverted growths seem to be little more 

 than hypertrophy of otherwise normal structures. Such growths 

 are highly vascular and more or less benign. Tissues which are 

 present ordinarily in certain standard definite patterns, and the 

 development of which does not extend beyond the usual range 

 of so-called normal size, may for unknown reasons take on ac- 

 celerated and excessive growth in mass. Other types represent 

 overgrowth of tissues that have, so to speak, run wild. They 

 grow rapidly and without restraint. Cells from such masses be- 

 come separated, are carried away by blood or lymph and grow 

 freely, forming new masses or metastases in any new locations 

 in which they may happen to come to rest. 



