TUMORS. 



275 



siderin are frequently found in tumors after hemorrhai^c into the 

 tumor tissue. 



Clinical Consideration. — Tumors are benign or malign. 

 ISenign tumors are usually encapsulated, i. e., they grow only 

 by interstitial expansion ; are conii)osed of adult or matured 

 tissue ; have no tendency to recur when removed, and have only 

 a mechanical effect upon the body in which they occur. Malign 

 tumors are usuallv not encapsulated ; thev grow bv peripheral 

 infiltration; are usually composed uf embrvonic tissue; fre- 

 ciuently recur wdien removed, and have a tendency to kill by 

 absorption of the metabolic products which are deleterious to 

 the body. ^lalign tumors of domestic animals are not as fatal 

 as thev are in the human. ]\Iany horses affected with sarcomata 

 have been permanently relieved by operation. 



Etiology. — There are some predisposing factors as heredity 

 and breed peculiarities that are frequently involved in the devel- 

 opment of tumors. Cadiot refers to a family of dogs in which 

 the females were affected with carcinomata of the mammae for 





^r^^t 



Fig. 



139. — Photograph of a horse affected with an ocular Epithelioma. 



This was a scam"? of n wirr cut 



