THE MICROSCOPE IN PATHOLOGY. 289 



Histologically, the forms of cancer resemble each other 

 in consisting of cells of an epithelial type, without inter- 

 cellular substance, grouped in irregular nests within the 

 alveoli of a fibroid stroma (Fig. 235). 



The differences between various forms of carcinoma 

 are chiefly dependent on the greater or less proportion of 

 cells and fibrous stroma. The deposit of pigment, form- 

 ing melanotic cancer, as it is termed, may also be a cause 



FIG. 235. 



a 



Brushed-out stroma of soft glandular cancer, a. Section of cylinder of cancer-cells. 

 b. Trabeculse of the stroma. c. A single spindle-cell, which extends from one trabecula 

 to another, and by the separation of basis-substance along its protoplasm gives the im- 

 pulse to the formation of a new trabecula of the stroma. d. Round-celled infiltrate in 

 the interior of the trabeculse of the stroma. 1-300. After RIXDFLEISCH. 



of variety ; so also ossification of the stroma (osteoid cancer) 

 and the multiplication and enlargement of the vessels, as 

 in fungus hcematodes ; but for the purposes of study the 

 three forms referred to are sufficiently characteristic. 



A difference of opinion exists as to the origin of the 

 epithelial-like cells in cancers. Billroth and others regard 

 them as starting only from pre-existing epithelium, while 

 Yirchow, Bindfleisch, etc., consider that they may be also 



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