TUMORS 



483 



lumps, or masses, possessing the firmness and hardness of bone, and in 

 the centre is found a soft tumor surrounded by a bony cyst. Sooner or 

 later the soft parts penetrate the bony envelope and certain of the fluid 

 escapes. 



4. The Papilloma. — A benign tumor originating from a hyperplasia 

 of the fibrous stroma of the cutaneous and mucous membrane, with a 

 proportionate formation of connective tissue. Papillomata are divided 

 into the hard and soft varieties. 



The hard papilloma or wart is a neoformation of the papillae of the 

 skin and of the epidermis. Warts differ very much in size, from a lentil 

 to the size of a large pea. The external covering of a wart is very often 

 hard and firmer than that of the connective tissue, so that the surface is 

 surrounded by a firm, hard, horny covering (horny warts). The reverse 



Fig. 175. — Multiple formation of warts. 



is found in the case of the soft, fleshy warts. These little growths are 

 found on the skin of dogs of all ages; as a rule on the head and back, but 

 also in other regions, and they frequently disappear without any treat- 

 ment (Fig. 175). Now and then the horny warts grow to a very large 

 size and form what are called "cutaneous horns." Such are found on 

 the forehead, the ear, and the flanks. They are generally seen in old 

 dogs, and at times have a tendency to be malignant. Enormous nvimbers 

 of warts are sometimes seen in the mouth, on the buccal mucous membrane 

 and tongue, and that they can be reproduced by inoculation has been 

 proved by McFadyean and Holding. 



A variety of the papillomata is the flat condyloma. These are 

 certain marked malformations which have the shape of a papilla, but as 

 a rule are ramified and divided, forming coxcomb-like or cauliflower 

 collections. In some cases they appear as true papillomata, particularly 

 as a sarcomatous formation. As a rule they appear on regions other 

 than the skin, such as the lips, cheeks, and prepuce, and also upon the 

 buccal mucous membrane. They are generally salient and bleed easily, 



