PATHOGENIC BACTERIA. 325 



times, involution forms. It is motile and has a flagellum 

 at one end. It liquefies gelatin much more rapidly than 

 the spirillum of cholera, and the colonies in gelatin develop 

 more rapidly. At the end of twenty-four hours the colo- 

 nies are uniformly circular, larger than those of the spiril- 

 lum of cholera, and uniformly granular, when slightly 

 magnified. On the other culture-media the growths are 

 usually whitish. On potato it produces an abundant, moist, 

 grayish-yellow deposit, and grows at the room temperature. 

 It liquefies blood-serum; milk becomes acid. In peptone 

 solution it does not form indol. It is less pathogenic to 

 animals than the spirillum of cholera. It was supposed by 

 its discoverers to be the cause of cholera nostras, but it ap- 

 pears to have no relation to that disease. 



Spirillum Milleri. A comma-shaped organism resem- 

 bling vibrio proteus in many respects, and probably ident- 

 ical with it. In gelatin it grows more rapidly, and produces 

 liquefaction more rapidly than the spirillum of cholera. 

 On gelatin plates, at the end of twenty-four hours, the 

 colonies are uniformly circular and granular, lying in little 

 depressions resulting from the liquefaction of the gelatin. 

 Its growths in the other media are not characteristic. It 

 liquefies blood-serum. It does not produce indol. It is 

 less toxic to animals than the spirillum of cholera. It was 

 isolated by Miller from a carious tooth. 



See also Spirillum sputigenum, Part III. 



Spirillum tyrogenum (of Deneke). A comma-shaped 

 organism not so large as the spirillum of cholera. It is 

 motile, having a flagellum at one end. It does not form 

 spores. In cultures, genuine spirilla may develop. Gelatin 

 is liquefied more rapidly than by the spirillum of cholera, 

 and the colonies develop more rapidly. The circumference 

 of the colony is round, the surface may appear somewhat 

 granular, and it has a greenish-brown color, seen under 



