121 



CHAPTER VII. 



Malignant Tumours. 



botryomycosis scirrhous cord actinomycosis melanosis. 



The general meaning of a tumour is a " swelling." The most 

 readily observable characteristics of malignancy in a tumour are : 

 a tendency to recur if locally removed; to extend to tissues other 

 than that in which it first appeared; and to invade distant parts. 

 These properties are of course absent in benign swellings, such as 

 splints, warts, and capped hocks. 



Botryomycosis 



is a diseased state of the tissues set up by the presence of special 

 micro-organisms, which Rivolta found in scirrhous cord in 1879, 

 and which he called discomyses equi. They are also termed 

 hotryomyces. They are often met with in scirrhous cord, poll evil, 

 fistulous withers, and in tumours which form on various parts of 

 the surface of the body. In all these cases, they appear to act as an 

 aggravation of an already existing wound, and not as an original 

 cause. It is probable that the Indian disease, bursatee, is due to an 

 allied parasite. Cadiot and Almy state that the majority of fibrous 

 tumours which have suppurating sinuses, are due to botryomyces. 

 Bollinger has found these microbes in fibrous tumours in the lungs, 

 and has given the name of botryomycosis to the disease originated 

 by them. It appears that these parasites, like actinomyces, find a 

 favoura])le residence in decaving- vegetable matter ; hence an 

 objection to bedding-down hoirses with open wounds (such as those 

 inflicted by castration), on peat moss, seems to be reasonable. 

 The irritation caused by the presence of this fungus, gives rise to 

 a growth of fibrous tissue which has a tendency to degenerate and 

 break up in the form of pus. 



