Cancer. 395 



In serial sections or in plastic reconstruction of tlie general tumor-picture 

 by means of the methods of planar modeling, one may always convince 

 himself of the interconnection of all the epithelial cords (Diirk). 



The connective tissue of the organ in which the epithelial cells 

 are in active cancerous proliferation, does not, however, act in a 

 purely passive manner, as a tissue shoved aside and compressed by 

 the epithelial growth ; but reacts by an inflammatory change which 

 in its chronic course leads to tlie production of a connective tissue 

 hyperplasia. The epithelial masses act precisely like foreign bodies, 

 attract leucocytes to them 1)y chemotaxis, the latter cells collecting 

 about the margins of the epithelium just as in a demarcating inflam- 

 mation and sometimes producing a marked cellular infiltration of the 

 connective tissue. At the same time the fixed connective tissue cells 

 proliferate and form a fibrous stroma (framework of the cancer) 

 of varying texture, containing young bloodvessels and enclosing epi- 

 thelial nests. 



The distinction from the typical fibroepithelial tumors [adenoma, 

 papilloma] lies in the fact that in the latter the epithelium and 

 connective tissue are united in common growth to form a tissue com- 

 plex, a compound tumor basis ; while in cancer in reality only the 

 epithelium is the basic tumor element, and the connective tissue 

 growing along with it is the result of a productive inflammation and 

 belongs properly to the organ in which the cancer is located. The 

 cancer stroma therefore is but the interstitial tissue of the affected 

 organ, involved bv inflammation. The epithelial elements of the 

 cancer develop in the organ in which the tumor originally (prim- 

 arily) gre\v, from cells, it is true, already present therein ; but the 

 epithelial cells of the organ are not uniformly changed into cancer 

 cells, do not all take part in the tumor construction. The growth 

 and extension of the latter involves invariably a fixed group of cells 

 acting as the germinal elements of the tumor, toward the multipli- 

 cation of which the other epithelial cells remain passive. 



The microscopic studies of Ribbert have furnished a number of 

 considerations which concern the histological production of the pri- 

 mary stage of this type of tumor, the start of the cancer formation. 

 Ribbert refers the origin of the growth to an isolation from the cel- 

 lular union in an organ of individual epithelial cells or a group of 

 cells, as an epithelial ingrowth, a separated bit of epiderm, or a 

 lobule of a gland : this subsequently assuming independent prolifer- 

 ation. This isolation from physiological connection is usually 

 brought about, as Ribbert recognized in microscopic sections in the 



