120 BACTERIOLOGY 



in all possible directions, and these peculiar projections 

 have procured for this micro-organism its name of ' multi- 

 pediculosus.' Gelatine is not liquefied. 



Bacillus neapolitanus. This microbe was first discovered 

 by Emmerich in the blood and in evacuations from the 

 corpses of cholera patients in Naples, and it was subsequently 

 ascertained to be present in normal faeces. Pathogenic 

 powers were ascribed to it, because a disease resembling the 

 cholera in human beings develops after the introduction of 

 considerable quantities of it into the bodies of guinea-pigs, 

 dogs, cats, and monkeys ; the introduction may be effected 

 subcutaneously, or into the abdominal cavity or the lungs. 

 Microscopic examination demonstrates the bacilli in all 

 the organs. There have, however, been objections made 

 by Weiser to ascribing pathogenic properties to it, and he 

 has shown that it is present in the air also. 



The bacillus appears as a short rodlet with rounded 

 ends and destitute of motile power, which forms on the 

 gelatine plate colonies resembling porcelain and lying at a 

 greater or less depth, of which the superficial ones spread 

 as a coating over the surface of the gelatine, and the deep 

 have a figure like that of a whetstone. In thrust-cultures 

 the more vigorous growth takes place on the surface (fig. 

 43). Gelatine is not liquefied, but loses its alkalinity, which 

 causes a clouding of the transparent jelly and a simultaneous 

 separation out of crystals of salt. If tincture of litmus is 

 added to the gelatine the blue colour disappears and becomes 

 changed to a red. A dirty white mass forms on agar 

 and potatoes. With regard to staining processes, it is a 

 special characteristic of this micro-organism that it does 

 not colour by Gram's method. Its resistance to external 

 influences is so great that it retains its vitality after being 

 frozen for twelve days and then thawed again. 



