PATHOGENIC BACTERIA. 263 



colony, SO that the surface of the gelatin may become covered 

 with so-called "swarming islands." 



The proteus grows on the usual media, tending to produce a 

 foul odor, decomposition and alkaline reaction. In urine it 

 converts urea into ammonium carbonate. 



This organism is one of those which were formerly described 

 under the name of Bacterium termo. It is among the most 

 common and widely distributed bacteria. It has been found 

 in decomposing animal and vegetable substances, in the feces, 



. *" '•\T "" ' 



-rrv^M-' 



Fig. 71. — Bacillus of Bubonic Plague. — {Yersin.) 



in the urine in cystitis and in the discharges of children suffering 

 from cholera infantum. It appears that this organism may 

 occasionally be pathogenic to man, causing pus formation, 

 peritonitis and even general infection.* Cultures injected 

 in considerable amounts may be pathogenic to animals. 



Bacillus of Bubonic Plague. — ^An oval or short rod-shaped 

 bacillus, with rounded ends, sometimes possessing a capsule. 

 It is not motile. It does not form spores. With the aniline dyes 

 the ends stain more deeply than the middle; this is called polar 



* Ware. Annals oj Surgery. Vol. XXXVI. 1902. 



