402 



Tumors. 



and develops in nodular prominences. By cropping out on the 

 surface, by perforation at one or more places of such a protuber- 

 ance, it ma}' become a direct surface growth with nodulated, uneven, 

 undulating elevations and more or less fissured surface. The in- 

 flammatory infiltration of the stroma, exaggerated by the entrance 

 of extraneous irritants into the exposed growth (contact with air, 

 intestinal contents, dirt or bacteria), is likely in such event to bring 

 about an ulcerative, foully suppurating destruction of the surface 

 of the cancer (cancerous ulcer). In case of penetration into asep- 

 tic cavities, especially the peritoneal (gastric cancer, cancer of the 



Fig. 110. 

 Cancer of tail of cow. 



intestine, cancer of kidney), transplantation of epithelial cells loos- 

 ened from the growth may be brought about by the intestinal peris- 

 talsis (by movements of the lungs, diaphragm and heart in the 

 chest) and give rise to extensive secondary carcinomatosis in the 

 serous membranes by their growth. The secondary formations are 

 at first small grayish-white nodules (iiiiliary carcinomatosis), but 

 later, by confluence of the enlarging cancerous foci and the accom- 

 panying inflammatory changes, a diffuse cancerous peritonitis or 

 pleuritis may be established. 



The morphology of the epithelial cells of which a cancer is com- 

 posed corresponds in a general way wifli that of the epithelium 



