Tumor Shapes; Sii^nificance of Tumors. 329 



tumors well tlefined from the normal tissues. They may develop 

 as nodes (tuherous growths) which lie embedded in the tissue 

 like the yolk within an egg, or niay protrude as tuberosities; they 

 may grow out from the surface of an organ as pedunculated 

 protuberances, with thick pedicle like a mushroom (fungous form), 

 or with slender pedicle and provided with free offshoots like a 

 polyp with its tentacles (polypous shape), or like a tree (den- 

 tritic), like a coral stalk or like cauliflower; or, in the infiltrating 

 varieties they may occasion a uniform szcelling of the affected 

 organ. [Anv tumor growing from a surface and provided with a 

 slender pedicle may be spoken of as a polyp or a polypoid 

 groii'th, whether branched or smooth. A form known as a flat 

 tabular s-u'elling is often encountered where upon a surface the 

 growth has produced a more or less uniform swelling with a 

 flattened surface, as is often seen where the surface of a growth 

 is opposed by a second surface causing pressure. The causes 

 determining the various shapes of tumors include such factors as 

 the mode of growth (central growth producing a regular ap- 

 pearance of the periphery, while infiltrative growths are apt to 

 be irregular and ragged in outline), pressure, (as just suggested 

 in connection with the flat tabular swelling, or the preservation of 

 the spheroidal shape of v node by the pressure from all sides by 

 the surrounding tissues, or where an analogous growth appears 

 as a tuberosity or polyp if developing close to a surface, being thus 

 relieved of pressure on the surface side), and the original structure 

 from which the tumor arises (as where a surface growth, a 

 papilloma, takes on ■ a villous type of branching following the 

 natural formation of villi from the original tissue, as in the 



intestine.)] 



The Pathological Significance of Tumors is determined pri- 

 marilv bv their location, their size and the mechanical pressure 

 which the}' exert upon the adjacent tissues. By pressure upon 

 the peripheral tissues a tumor as it grows in size occasions some- 

 times trifling and at other times serious disturbance of func- 

 tion, varying with the particular organ affected. A small 

 tumor in the brain or in the cranial cavity may by compression 

 of the fonuer or of the cerebral vessels bring about most intense 

 nervous troubles and terminate fatally; and by obstructing the 

 larynx, gullet or intestinal canal a comparatively small growth may 

 endanger life. Pressure upon bloodvessels may occasion a great 

 variety of circulatory disturbances. But, on the other hand, even 



