Bacillus Proteus Vulgaris 325 



Immunity.— Immunity against pyocyaneus infection develops 

 after a few inoculations with attenuated or sterilized cultures. 

 These are easily prepared, the thermal death-point determined by 

 Sternberg being s6°C. It also follows injection of either the endo- 

 toxin or the exotoxin. In the immunity resulting from the treat- 

 ment with bacterio-vaccines the serum of the animal becomes 

 agglutinative and bactericidal; in the immunity resulting from 

 treatment with the exotoxin, antitoxin is produced. 



Bacillus Proteus Vulgaris (Hauser) 



General Characteristics. — An actively motile, flagellated, non-sporogenous, 

 non-chromogenic, liquefying, aerobic and optionally anaerobic, doubtfully 

 pathogenic, aerogenic bacillus, easily cultivated on artificial media and readily 

 stained by the ordinary methods, though not by Gram's method. 



This bacillus was first found by Hauser* in decomposing animal 

 infusions, usually in company with two closely allied forms, Proteus 

 mirabilis and Proteus zenkeri, which, as the experiments and 

 observations of Sanfelice and others show, may be identical with it. 

 According to Kruse, it is quite probable that the mixed species 

 formerly called Bacterium termo was largely made up of the proteus. 



Distribution. — The organism is a common saprophyte and is 

 very abundant in water, earth, and air. It is to be expected wher- 

 ever putrefactive change is in progress. It is a common mistake for 

 the novice to look upon it as a member of the Bacillus coli group. 



Morphology. — The bacilli are variable in size and shape — pleo- 

 morphic — and are named proteus from this peculiarity. Some differ 

 very little from cocci, some are more like the colon bacillus in shape, 

 others form long filaments, and occasional spirulina forms are met 

 with. True spirals are never found. All of the forms mentioned 

 may be found in pure cultures of the same organism. The diameter 

 of the bacillus is usually about 0.6 fi, but the length varies from 1.2 

 /i or less to 4 /i or more. No spores are formed. The organisms are 

 actively motile. The long filaments frequently form loops and 

 tangles. Flagella are present in large numbers. Upon one of the 

 long bacilli as many as one hundred have been counted. Involution 

 forms are frequent in old cultures. 



Staining. — The bacilli stain well by the ordinary methods. 

 Gram's method usually fails. 



Cultivation. — The proteus is easily cultivated and grows well in 

 all the artificial media. 



Colonies. — Upon gelatin plates a typical phenomenon is observed 

 in connection with the development of the colonies, for the most 

 advantageous observation of which the medium used for making 

 the cultures should contain 5 instead of 10 per cent, of gelatin. 

 Kruse t describes the phenomenon as follows: 



* "Ueber Faulnissbakterien," Leipzig, 1885. 

 t Fliigge's "Die Mikroorganismen." 



