EPITHELIAL CANCER. 447 



gradually increased in size, until it became unsightly, and inter- 

 fered with the application of the saddle-girths. 



EPITHELIAL CANCER. 



Epithelial cancerous tumours, also known as epithelioma 

 or cancroid, consist of a fibrous stroma, in which papillse and 

 epithelium are found greatly multiplied and enlarged. The cells, 

 when microscopically examined, are found to be numerous, flat, 

 round, oval, or elongated, containing a simple nucleus; and 

 other cells containing large nuclei, which appear as if in process 

 of development into cells. They differ but little from the 

 natural epithelial cells of the part ; and as the minute structure 

 of this form deviates least of all the cancers from the natural 

 structures upon which it grows, so its course and history exhibit 

 but little malignancy. 



Its chief site is the skin and mucous membranes, but particu- 

 larly at the junction of the two; as the mouth of mucous 

 orifices, the vulva, anus, eyelids, and edges of the mouth. It is 

 a very rare form in the lower animals ; arises from some 

 previous local disease or injury ; and is seen more frequently in 

 dogs than in the other domesticated animals, — (Fig. 93.) 



Fig. 93. — Section of epithelial cancer from palate of the ox, showin!;f larsre 

 flattened cells, with numerous smaller ones enclosed in a fibrous matrix. 

 250 diam. 



