Cultivation Pathogenesis 



cultures are rich in spores, which are very small and develop 

 upon the most superficial portions only. 



Cultivation. Bouillon. In bouillon the organism de- 

 velops in the form of colorless masses irregular in size 

 and shape, some of which float upon the surface, while 

 others sink to the bottom of the liquid. Sometimes the 

 surface is covered by an irregular fenestrated pellicle of a 

 gray color. 



Agar-agar. Upon agar-agar (glycerin agar-agar is pref- 

 erable) the growth develops in the form of small, discrete, 

 irregularly rounded, opaque 

 masses of a yellowish-wliite 

 color. The surface of the col- 

 onies is irregular and uneven, 

 the appearance resembling a 

 lichen (see Fig. 115). 



Potato. Upon potato a pale 

 yellow, dry, wrinkled, scaly 

 growth occurs. 



Blood-serum. The growth 

 upon blood-serum is similar to 

 that upon agar-agar, but is less 

 luxuriant. 



Milk. In milk the organism 

 produces no coagulation and 

 does not alter the reaction. 



Pathogenesis. The micro- 

 organism of farcin du boeuf is 

 pathogenic for guinea-pigs, cat- 

 tle, and sheep. Man, dogs, rab- 

 bits, horses, and asses are im- 

 mune. 



When a virulent culture, or 



some pus, containing the micro-organisms, is subcutaneously 

 injected into a guinea-pig, an abscess forms at the seat of 

 operation. Not long afterward the lymphatic vessels and 

 glands of the region swell and indurate, and extensive phleg- 

 mons form, which rupture externally and discharge pus. 

 The animal becomes extremely ill, seems about to die, but 

 slowly recovers. 



In the cow and the sheep subcutaneous inoculations 

 result in the formation of an abscess relatively less exten- 

 sive, which evacuates, ulcerates, indurates, and seems to 



Fig. 115. Streptothrix of 

 farcin du boeuf growing on 

 glycerin agar-agar. 



