PATHOGENIC STBEPTOTHBICES. 367 



On potato, it grows as a dense, widely spreading, vel- 

 vety membrane; pale brown at the centre and white at 

 the periphery. The potato takes on a dark-brown color 

 and becomes very moist and dark ; coffee-colored gran- 

 ules appear upon the surface of the growth. 



In bouillon the growth assumes a puff-ball appear- 

 ance. The medium assumes a deep coffee-brown color, 

 and ultimately a mycelium growth appears upon the 

 surface and throughout the fluid. 



"When grown in potato infusion (20 grammes of potato 

 boiled in water, filtered and made up to a litre), 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 polyhe- 

 dral cells, together with some short, thick segmented 

 hyphse. The walls of these cells have a black appear- 

 ance, 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 ani- 

 mals 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 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 



