380 Tumors. . 



tumor and within the cells. The latter elements are seen as 

 variably shaped, irregularly rounded, fusiform and branched 

 cells, their cytoplasm usually so thickly loaded with the dark 

 brown granules that the nucleus is obscured ; at places, however, 

 they may be found entirely free from pigment. The cells are 

 usually so closely packed together that their outlines cannot 

 always be dififerentiated. The tumor tissue is very clearly 

 defined from the rest of the tissues, into the lymph spaces of 

 which the neoplasm can be seen to be extending its way, afford- 

 ing an excellent demonstration under the microscope of the 

 mode of propagation of these growths. The cells are so easily 

 loosened in the softer specimens that the tumor mass may stand 

 out like thick pultaceous material ; Csokor has observed in the 

 case of a horse with the intestinal mucous membrane (colon) 

 the seat of melanoma, the discharge of black fecal matter ; and 

 Bollinger, Bruckmiiller and Semmer have found the pigment 

 gramdes in the blood (melan:cmia). 



The pigment material known as melanin, certainly does not 

 come from the blood (iron free), but is formed by a specific 

 activity of the chromatophorous cells, as Berdez and Nencki 

 have shown ; the important proportion of sulphur in its compo- 

 sition suggests that it is a derivative of albuminous bodies. 



The orisfin of melanomata is necessarilv in some wav related 

 to developmental disturbances which give rise to excessive pro- 

 duction or misplacement of pigment cells; their occurrence as 

 congenital tumors and the fact that in man the growths are 

 known to frequently take their start from congenital pigment 

 moles of the skin, are evidence in favor of such a view. 



The malignancy of these growths is not uniform; as above 

 stated, some may remain in their primary situation for years 

 without appreciable enlargement, and may not recur when re- 

 moved, but others, especially the softer forms, spread rapidly and 

 widely and give rise to great numbers of secondary nodes. [The 

 melanotic sarcoma of man. most commonly met in the eye, is ex- 

 tremely malignant, ranking probably first of all in the list of sar- 

 comata in this respect.] 



Endotheliomata, Peritheliomata, Cholesteatomata. 



By the term endothelioma is meant a tumor which is com- 

 posed of endothelial cells of connective tissue derivation, espe- 

 cially those of blood vessels and lymph vessels, as well as those 



