474 PA THOGENIC BA CTERIA . 



plate. Often from the radiated central part of the colony 

 peculiar zooglea are formed, having a sausage- or screw- 

 shape, or wound in spirals like a corkscrew. The 

 younger colonies, which have not yet reached the surface 

 of the gelatin, are more compact, rounded or nodular, 

 later covered with hair, and then becoming radiated and 

 like the superficial colonies.'' 



When the culture-medium is more concentrated, or the 

 culture one that has been frequently transplanted, the 

 phenomenon is much less marked and sometimes does 

 not take place at all. 



Puncture-cultures in gelatin are not at all character- 

 istic. They show a rapid stocking-like liquefaction of 

 the gelatin, extending so as to take in the entire gelatin 

 in the tube in a few days. Anaerobic cultures do not 

 liquefy. 



Upon agar-agar the bacillus grows with the production 

 of a moist, thin, transparent, rapidly extending layer 

 which probably rarely reaches the sides of the tube. 

 Upon agar-agar plates the wandering of the colonies is 

 also said to occur. 



Upon potato the growth is in the form of a dirty-look- 

 ing, smeary patch. 



In culture-media containing either grape- or cane-sugar 

 fermentation occurs both in the presence and in the 

 absence of oxygen. Milk-sugar is not decomposed. 



When grown in milk the medium is coagulated. 



In its growth the bacillus usually produces a strong 

 alkaline reaction. Indol and phenol are formed from 

 the peptone of the culture-media. Nitrates are reduced 

 to nitrites, and then partly reduced to NH 3 . In most 

 culture-media not containing sugar the bacillus pro- 

 duces a very disagreeable odor. 



It is a question whether the Bacillus proteus is to be 

 ranked among the pathogenic bacteria. Small doses of 

 it are harmless for the laboratory animals; in large doses 

 it produces abscesses. A toxic substance undoubtedly 

 results from the metabolism of the organism, and is the 



