264 MANUAL OF BACTERIOLOGY. 



mune to subsequent infection with this organism. It ap- 

 pears that an antagonism exists between the products of 

 the bacillus pyocyaneus and the anthrax bacillus. Rabbits 

 which have been inoculated with cultures of the anthrax 

 bacillus may recover if they are injected shortly after with 

 a culture of the bacillus pyocyaneus. 



Bacillus proteus. A bacillus with rounded ends, vary- 

 ing much in length, breadth .4 to .6 ^ ; frequently appear- 

 ing as short ovals like micrococci; sometimes growing out 

 into long filaments, so that it is said to be pleomorphic. 

 Rounded involution forms occur. It is not stained by 

 Gram's method. It is motile. Spore formation has not 

 been observed. It is aerobic and facultative anaerobic. It 

 grows rapidly at ordinary temperatures. This organism 

 was originally described by Hauser as three different 

 species proteus mdgaris, which was said to liquefy gel- 

 atin rapidly, proteus mirabilis, which liquefied gelatin 

 slowly, and proteus Zenkcri, which did not liquefy gelatin. 

 It seems probable that these organisms were, in fact, 

 varieties of the same species, now called bacillus proteus. 

 Upon gelatin-plates the colonies present a characteristic 

 phenomenon, when seen under the low power, in the pro- 

 jection of processes which subsequently change their form 

 and position, and which may become entirely detached 

 from the original 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 pro- 

 duce foul odor, decomposition and alkaline reaction. In 

 urine it converts urea into ammonium carbonate. 



This organism is one of those which were formerly de- 

 scribed 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 sub- 

 stances, in the feces, in the urine in cystitis, and in the dis- 



