ACTINOMYCETES 439 



becomes very moist and dark; coffee-colored granules 

 appear upon the surface of the growth. 



In bouillon the growth assumes a puff-ball appearance. 

 The medium assumes a deep coffee-brown color, and ulti- 

 mately a mycelium growth appears upon the surface and 

 throughout the fluid. 



When grown in potato infusion (20 grams of potato 

 boiled in water, filtered and made up to a liter), the growth 

 is characterized by the appearance of black granules in the 

 midst of the mycelium. The black granules consist of 

 closely packed spherical or polyhedral cells, together with 

 some short, thick segmented hyphee. The walls of these 

 cells have a black appearance, and masses of them are black 

 and opaque under the microscope. 



On agar-agar, growth appears as a grayish mesh-work of 

 widely spreading filaments. In old cultures black granules 

 (sclerotia) appear among the filaments. No growth occurs 

 in the depth of the medium. 



No results were obtained by the inoculation of animals 

 with either the material direct from the tissues or with pure 

 cultures. 



The tissue from which this fungus was obtained con- 

 sisted, briefly, of a more or less atypical connective-tissue 

 new-growth, with numerous areas of suppuration marked by 

 the presence of the black granules just described. 



On histological study of the tumor the primary effect 

 produced by the parasite appears to be the development 

 of nodules of epithelial cells and of giant cells from the 

 tissues immediately about them. Later, suppuration of the 

 nodules and abscess formation occur. This in time gives 

 rise to excessive development of granulation and connective 

 tissue. 



