Page:The New International Encyclopædia 1st ed. v. 19.djvu/609

* TULLOCH. 529 TUMOR. Saint Mary's College, in the University of Saint Andrews. In 18.59 lie was appointed one of her Majesty's chaplains for Scotland. He was highly appreciated as a broad-minded, progressive the- ologian, was moderator of the General Assembly in 1S78, was appointed dean of the chapel royal and dean of the Thistle in 1.S82, and died at Torquay. Among his works are: Theism (S~ui) ; Leaders of I lie Reformation ( 1859; .3ded. 1S8;J) ; English Puritanism and Its Leaders (1801) ; Be- (/inning Life (1862); Rational Theology and Christian Philosophy in England in the tSeven- ternth Cenltiri/ (1872; 2d ed. 1874): The Chris- tian Doetrine of iS'i'n (187fi) ; Modern Theories in Philosophy and Religion (1884); Movements of Religious Thought in Britain During the Nine- teenth Century (188.5). Consult his Life bv Mrs. Oliphant (London, 1888; 3d ed. 1889). TULTCHIN, tool'chen. A town in the Gov- ernment of Podolia, Russia, 100 miles east of Kamenetz-Podolsk. Population, in 1897, 19,202. TULtrS, too'looz. One of the civilized, or half- civilized. Dravidian peoples of Hindustan. They inhabit the coast region about Mangalore, and number some .3.50.000. Their language is closely re- lated to ancient Kanarese. Consult: Brigel, Grom- niar of the Tulu Language (Mangalore, 1872). TUMACO, too-mli'ko. A seaport of the Depart- ment of Cauca, Colombia, 1.50 miles southwest of Popayfln (Map: Colombia, B 3). It has an extensive locffl steamer trade with Guayaquil and Panama. Population, about 0000. TUMBLE-BUG. See Dung-Beetle. TUMBLEWEEDS. Plants, chiefly annuals, especially abundant in prairie regions. They scatter their seeds as they are rolled or tumbled from place to place by the wind. See Seed. TUMOR (Lat., swelling, state of being swol- len). In medicine, an abnormal increase in size of an area of tissue or of an organ : a swelling, excluding swellings occurring in the covirse of simple inflammation. In pathology, a tumor is an overgrowth or hypertrophy, deviating in size and shape from the normal, with an inherent power and method of growth, this growth being independent of the rest of the body. Pathologists include under the term tumor ulcerations and their boundaries, when such boundaries are com- posed in part, at least, of new tissue. Pathologi- cally, then, a tumor is a growth of new tissue in the body wdiieh causes local increase in the size of the part or organ in which it occurs. Tumors are distinctly pathological, subserving no useful physiological purposes; in fact, usually growing at the expense of useful tissues and organs. The tissues of which tumors are composed conform to the same general types as are nor- mally found in the bodj', with the exception th,at in the case of some tumors there is a tendency toward the reversion of the tissues to embryonic forms. Tumors usually originate in tissues which are of like structure with that of the tumor itself. Thus connective-tissue tumors usually take their origin in connective tissue, epithelial tumors in epithelium, etc. When such tumors remain confined to the tissues in which the}' originate they are known as homologous tumors. When, however, they spread to surround- ing tissues of a ditt'erent type, or when, as oc- curs in the case of malignant tumors, new tumors are started, in distant tissues and organs by means of the dissemination of bits of tissue from the primary growth through the blooil and lym]ih, they are known as heterologous tun'ors. Some tumors are congenital, notably the na;vi or va.scular tumors. In some cases there appears to be a distinct hereditary tendency to tumor formation ; yet ideas as to the heredity of can- cer are grossly exaggerated in the minds of the laity, for, while the occurrence of cancer in sev- eral generations has been observed, the absence of cancer in the children and grandchildren of persons who have been afflicted with the most malignant forms has been equally noted. In- flammation resulting from injury, especially from long-continued slight irritation, seems to be a frequent cause of tumor formation, injuries to bone being quite frequently followed by the development of osteo-sareoma. Also injur}', as for example from a blow or from a fall, not in- frequently precedes the development of cancer of that organ. Cancer of the tongue or lip is often apparently traceable to the constant irri- tation of a broken clay pipe or of a rough tooth. In general it would seem that tumors of the con- nective-tissue type (sarcoma) most frequently follow a single injury, as for example from a blow, while tumors of the epithelial type (epithe- lioma, carcinoma) are more apt to occur as the result of frequently repeated slight irritations. Chronic inflammation seems to bear some causa- tive relation to tumor formation. This is evi- dent in the frequent association of carcinoma of the liver with cirrhosis of that organ. Again, malignant tumors or cancer not infrequent!}' find their starting point in such local malformations as skin napvi. Age and sex also play important roles among the predisposing causes of tumors. Thus epithelial cancer or carcinoma is rare in persons under thirty years of age. Cancer of the breast is far more common in the female, this being undoubtedly due to the greater f^inctional activity of that organ in the female. Cancer of the tongue and lip is, on the other hand, much more conunon in the male. This is probably due to the fact that frequent irritation from smoking is much more common in that sex. As to the primary causative factor in the pro- duction of tumors we have as yet very imperfect knowledge. Of the many theories which have been advanced in explanation of tumor growth, probably the most ingenious anil the one to which at present greatest credence is given is one advanced by Cohnheim. According to his theory, during embryonal development some cells stop developing. These cells may either remain in among tissues of tlicir own kind or may be- come displaced in the course of further develop- ment of the surrounding tissues and so come to lie among other tissues. Such cells lie dor- mant for long periods until something in their environment calls them into activity, when they proceed to develop with all the potential growth of young embryonal cells. Furthermore, being unlimited by the wear and tear of physiological function, as is the case with normal tissues and organs, they are free to devote their entire ener- gies to growth. For these two reasons, the high potentiality for growth of embryonal tissue and the lack of any control of the growth by the re- quirements of function, tumor tissue, especially of the embryonal type, is apt to be characterized by a sort of irregular, wild cell-growth quite ditl'erent from the orderly arrangement of cells in