BACILLUS PROTEUS VULGARIS 377 



Bacillus Proteus Vulgaris. 



This bacillus, which is one of the most common and widely dis- 

 tributed putrefactive bacteria, was discovered by Hauser (1885) along 

 with other species of proteus in putrefying substances. These bacteria 

 were formerly included under the name "bacterium termo" by pre- 

 vious observers, who applied this name to any minute motile bacilli 

 found in putrefying infusions. 



Morphology. Bacilli varying greatly in size; most commonly occur- 

 ring 0.6/* broad and 1.2, long, but snorter and longer forms may also 

 be seen, even growing out into flexible filaments which are sometimes 

 more or less wavy or twisted like braids of hair. 



The bacillus does not form spores, and stains readily with fuchsin or 

 gentian violet. 



Biology. An aerobic, facultative anaerobic, liquefying, motile bacillus. 

 Grows rapidly in the usual culture media at the room temperature. 



GROWTH ox GELATIN The growth upon gelatin plates containing 5 

 per cent, of gelatin is very characteristic. At the end of ten or twelve 

 hours at room temperature small, round depressions in the gelatin are 

 observed, which contain liquefied gelatin and a whitish mass consist- 

 ing of bacilli in the centre. Under a low-power lens these depressions 

 are seen to be surrounded by a radiating zone composed of two or 

 more layers, outside of which is a zone of a single layer, from which 

 amoeba-like processes extend upon the surface of the gelatin. These 

 processes are constantly undergoing changes in their form and posi- 

 tion. The young colonies deep down in the gelatin are somewhat 

 more compact, and rounded or humpbacked; later they are covered 

 with soft down; then they form irregular, radiating masses, and simu- 

 late the superficial colonies. But it is difficult to describe all the'forms 

 which the proteus vulgaris takes on in all the stages of its growth on 

 gelatin plates. When the consistency of the medium is more solid, 

 as in 10 per cent, gelatin, the liquefaction and migration of surface 

 colonies are more or less retarded. In gelatin-stick cultures the growth 

 is less characteristic liquefaction takes place rapidly along the line 

 of puncture, and soon the entire contents of the tube are liquefied. 



Upon nuirient agar a rapidly spreading, moist, thin, grayish-white 

 layer appears, and migration of the colonies also occurs. Silt is coagu- 

 lated, with the production of acid. 



Cultures in media containing albumin or gelatin have a disagree- 

 able, putrefactive odor, and become alkaline in reaction. Growth 

 is most luxuriant at a temperature of 24 C., but is plentiful also at 

 37 C. It is a facultative anaerobe and grows also in the absence of 

 oxygen, but the proteus then loses its power of liquefying gelatin. It 

 produces indol and phenol from- peptone solutions. The proteus 

 develops fairly well in urine, and decomposes urea into carbonate of 

 ammonia. 



Pathogenesis. This bacillus is pathogenic for rabbits and guinea- 

 pigs when injected in large quantities into the circulation, the abdom- 



