216 PATHOGENIC MICROORGANISMS. 



Its growth on blood-serum and agar is as isolated colonies 

 on the surface of these media. The colonies are yellowish 

 red and covered with a sort of fluffy down. After a few 

 weeks the colonies run together and form a thick wrinkled 

 mass which sinks into the media. 



On gelatin the growth causes slow liquefaction. On potato 

 the colony is yellowish red and limited in extent, has a viscid, 

 membranous appearance, and is slow in progress. In bouillon 

 it causes no clouding, but develops on the surface of the 

 medium as a distinct granular growth forming a membranous 

 film, which afterward sinks to the bottom of the tube. 



Pathogenesis. Cattle are the most frequently affected 

 animals, though the disease has been seen in swine, dogs, and 

 horses. The common location of the disease is in the jaw. 

 It is not transmissible from animal to man. Inoculations of 

 pure cultures are negative, though some observers have suc- 

 ceeded by intravascular inoculations in producing tumors from 

 which the fungus was obtained in pure cultures. 



The disease is sometimes quite prevalent among animals, and 

 appears to result from the ingestion of vegetable products which 

 contain the streptothrix. 



In the earliest stages the parasites give rise to tumors 

 resembling tuberculous growths, and as these reach a larger 

 size there is proliferation of the surrounding connective 

 tissue. The tumors are then very hard, resembling osteosar- 

 comata. Suppuration finally takes place, due to the action 

 of the fungus itself, or more probably to secondary infection 

 of the tumor by pus-producing organisms. 



The Other Pathogenic Streptothrices. 



The streptothrix of madura foot, described by Wright, in 

 the Journal of Experimental Medicine, 1898. and the Strepto- 

 thrix farcinicus, discovered by Nocard in 1888, in a disease 

 of cattle resembling farcy in horses ; the Streptothrix Eppin- 

 geri, discovered by Eppinger in a case of acute abscess of the 

 brain ; and the Streptothrix pseudotuberculosa, described by 

 Flexner in 1897, are of interest, and the reader is referred 

 to larger works on Bacteriology for their description. 



