388 Tumors. 



In the urinary and gall bladders of cattle, in the former also 

 of horses, dogs and swine, papillary mucous membrane prolifera- 

 tions occur, usually projecting as long villous, highly branched 

 growths with a common pedicle into the cavity of the viscus. like 

 the tentacles of a polyp {papilloma polyposum) ; they are usually 

 very soft, succulent, their connective tissue oedematous and per- 

 haps actually myxomatous (papilloma polyposum myxo'matodcs), 

 or in other cases the seat of a cellular infiltration and presenting 

 evidence of inflammatory involvement. Inflammatory changes 

 in the last named situations are so frequently accompanied by 

 mucous membrane proliferations that some causal relationship 

 may be assumed and the hyperplasia of the mucous membrane 

 regarded as a sequel to a productive inflammation (Zellhuber). 



Where the epithelium of the papillary growth of the skin is 

 not desquamated in scales, but in its active proliferation forms 

 thicker and thicker horny layers, there is produced a hard body 

 which continually grows more and more prominent and acquires 

 the form of a horn-like outgrowth, a cutaneous horn (coniii cuta- 

 neiim). These structures are very frequently seen in cattle, 

 especiallv in range cattle, occasionally attaining a length of half 

 a meter, growing from the forehead or neck, or as a short 

 conical horn from the skin of the udder. Now and then large 

 spirally curved cutaneous horns are seen in goats in the thoracic 

 and abdominal walls; in sheep in the car and back; in horses and 

 dogs as small claw-like horns in the car and in other parts of the 

 body. (For fuller description see Casper, Pathol, d. Gcschzviilste 

 b. Ticrcn. Wiesbaden, 1899; Kitt, Spcz. pathol. Anatomic. II. Aufl., 

 Stuttgart, 1901.) 



Papillomata and cutaneous horns are regarded as benign, non- 

 recurrent, persistently local new growths ; they manifest an unfavor- 

 able tendency only from their size and situation. 



* Adenoma. 



An adenoma, or [epithelial] glandular tumor, is a prolif- 

 eration of glandular tissue, with reproduction of its structural 

 type, in the forni of a tumor. Epithelium and a vascular con- 

 nective tissue stroma in definite structural relations constitute 

 glands, and the two forms of tissue in common contribute to the 

 formation of the adenoma. Whedier the epithelium was the 

 primary proliferating element and, as Borst believes, the con- 

 nective tissue cells took a relatively secondary part because 



