198 EPITHELIAL CARCINOMATA. 



parts are rare, as also are deposits in the neighbouring lymphatic 

 glands, which for the most part remain unaffected. 



Localities : stomach, large intestine, liver, ovary, mammary 

 gland. 



11. Epithelial Carcixomata. 



§ IG-i. Were we to take into account every variation in con- 

 sistency, colour and texture, we should find it difficult to get any 

 two specimens of epithelial cancer, taken from different parts of 

 the cutaneous and mucous systems, which could be viewed as 

 growths of an absolutely identical character ; so great is the 

 influence of the parent-soil, especially in the case of epithelial 

 cancer. We must content ourselves for the present with establish- 

 ing two main categories, corresponding to the two leading forms 

 of epithelium, the squamous epithelioma and the columnar epithe- 

 lioma. The former occurs chiefly, but not exclusively, on sur- 

 faces clothed with flattened epithelium, the latter on such as are 

 lined with the columnar variety ; }'et squamous epithelioma is 

 not excluded from mucous membranes clothed with columnar 

 epithelium, e.g. the gastric mucous membrane. 



§ 165. Squamous Epithelioma (epithelioma, epidermic can- 

 cer, cancroid) forms a white, dense mass of somewhat dry 

 quality, which presents on section either an aspect entirely homo- 

 geneous, or affords at most but vague indications of its finer 

 structure. To the finger it imparts a marked sense of resistance, 

 which however is dull and inelastic ; on squeezing it forcibly 

 from the side, contorted threads of a milk-white colour protrude 

 from its surface ; these have been very aptly compared to the 

 so-called " comedones " which may be squeezed from the seba- 

 ceous glands upon the nose. These threads readily break up in 

 water ; a cellular emulsion being formed resembling the milky 

 juice of cancer ; but the suspended cells are all true speci- 

 mens of squamous epithelium, indistinguishable from those 

 which line the oral cavity. Certain peculiarities of a minor sort 

 in the form of the individual cells will be more properly discussed 

 when we come to consider the appearances seen in tranverse 

 sections. The nuclei are always of large size, ovoid, double- 

 contoured and furnis^hed with one or more large and lustrous 

 nucleoli. 



