342 TUMORS. 



Carcinoma, or Cancerous Tumor. We call " carcinoma" a 

 neoformation which has originated by an accumulation of epithelial 

 cells. These cells possess the peculiar property of forming meta- 

 stases through the various lymphatic glands, and producing a gene- 

 ral cancerous infection of the body, and are, therefore, considered 

 malignant. Almost all the cancerous forms are distinguished by 

 their tendency to regressive metamorphoses. These are mucous, 

 colloid, and fatty degeneration with cystic formation, calcification, 

 cicatricial contraction, and in superficial carcinoma of the skin 

 and mucous membranes ulcerous disintegrations with formation of 

 a purulent centre are called " phagedenic " tumors. 



We recognize the following forms of carcinoma : 



Squamous Cancer, or Cellular Epithelioma. This occurs in the 

 cutaneous membrane and in all the mucous membranes containing 

 squamous epithelium, as the mouth, throat, larynx, external gen- 

 itals, bladder, and urethra. 



This affection in the cutaneous membrane, cutaneous cancer or 

 cancroid, is very often seen in old animals, and occurs in any 

 part of the body. It originates as diffused, thickened, or warty 

 growth of the skin, becoming rapidly extended over its surface, 

 and finally altered into cancerous tumor (ulcus rodens). It is a 

 peculiar fact that this cancerous growth may accumulate rapidly 

 for a short time, and then remain stationary without increasing 

 any more. 



Squamous cancer or cellular epithelioma, which appears in the 

 mucous membranes, especially in the vagina, which deserves spe- 

 cial mention, has a great tendency to extend superficially, followed 

 by a cancerous disintegration, also by a constant, bloody, purulent 

 discharge. 



Cylindrical-cell Cancer. We observe this in the mucous mem- 

 brane of the digestive tract and the uterus. Cancer of the stomach 

 is of some importance, as it has been recognized in a number of 

 post-mortems. Its existence during life can only be guessed at by 

 frequent vomiting of more or less blood. 



Cancer of the Glandular Tissue. This is found in all glandular 

 organs and especially in the mammaries of old bitches. This 

 cancer of the mammaries is marked by the following character- 

 istics : 



It is of slow growth, is particularly hard and firm, and has a 



