YEASTS AND MOLDS 215 



growth occurs best. Temperature of 37 C. most suited. 

 The colonies near the surface become colored red. 



Agar. Glazed colonies, at first colorless, then rose-colored, 

 about the size of a pea, with the central part umbilicated and 

 pale. Gradually the rose color fades. 



Acid Potato. A slow and meager growth. 



Pathogenesis. Only local reaction has been caused by inocu- 

 lation in animals. In man the disease usually follows a slight 

 injury and attacks the leg or foot, slowly forming a nodular 

 growth, which in the course of months or a year begins to 

 soften and ulcerate, and with the seropus are discharged 

 numerous little granules, some black, some pink, containing 

 mycelia. The limb becomes much deformed, the tissue 

 vascularized, and the degenerated area filled with the strepto- 

 thrix filaments. 



Staining. The organism itself stained with ordinary stains. 

 Gram's method for the tissue. 



Streptothrix Farcinica (Nocard) ; Bovine Farcin du 

 Boeuf . Origin. A disease affecting cattle and giving rise to 

 tubercle-like lesions in the lungs, liver, and spleen. Common 

 in France. 



Form. Small interwoven mass of threads arranged in tufts 

 found in the centers of the tubercles. 



Culture. At body-temperature in various media. 



Bouillon. Colorless masses, irregular in size and shape. 



Agar and Gelatin. Small, rounded, opaque colonies, thicker 

 at the periphery. 



Potato. Rapid growth of pale-yellow, dry scales, consisting 

 of many spores. 



Pathogenesis. Pure cultures introduced into the peritoneum 

 of guinea-pigs give rise in nine to twenty days to tubercle-like 

 lesions. Subcutaneous injections cause abscesses with sec- 

 ondary involvement of the lymphatics, ending in recovery. 

 Dogs, horses, and rabbits are immune. 



Staining. Wright's double stain for tissues; also Gram's. 



