PATHOGENIC BACTERIA. 31^ 



membrane, sometimes followed by ulceration. It is commonest in Austria and 

 Italy. It has been seen in America only very rarely. 



The organisms may be stained in the diseased tissues, but their detection is 

 a matter of considerable difficulty, and they are not always found. It is not 

 yet certain tliat they are the caUse of rhinoscleroma. 



Bacillus Mycogenes.*— A plump, short bacillus, less than 

 I M in breadth, possessing no fiagella, non-motile, does not 

 form spoes; capsules are seen in preparations from tissues of 

 inoculated animals and in milk cultures, rarely in preparations 

 from agar cultures. The organism occurs singly or in pairs, 

 and even in longer filaments. Gram positive in tissues, but 

 negative in cultures. 



The growth on agar is porcelain white and viscid. In all 

 liquid media viscidity is very marked. Gelatin is not liquefied. 

 Coagulated blood-serum not liquefied. "Nail-head" growth 

 shows in stab cultures. Milk is coagulated in one to five days. 

 Casein not digested. Litmus is reduced. Growth on potato 

 is brown and slimy, but there is no gas formation. Indol 

 negative. None of the sugars are fermented. 



Very pathogenic for rabbits and guinea-pigs. Rabbits are 

 killed in eighteen hours by subcutaneous injection of y-^-g- c.c. 

 of a twenty-four hour beef-broth culture, guinea-pigs in less 

 than fifteen hours by the same dose. 



Bacillus Pyocyaneus. — A shm bacillus with rounded ends. 

 It is motile. It does not form spores. It is decolorized by 

 Gram's method. It is aerobic; grows well at ordinary tem- 

 peiatures; liquefies gelatin, and grows on the ordinary culture- 

 media. Cultures persent a blue or green color, especially in 

 transparent media. This color is not confined to the growth 

 itself, but a blue or green fluorescence spreads over the whole 

 medium. In an old agar culture the color may become very 

 dark. The pigment forms in the presence of oxygen, and is 

 due, at least in part, to the ptomaine, pyocyanin. On potato 



*Ralph T. Edwards. Journal oj Infectious Diseases, Vol. II., No. 3. 1905. 



