244 BACTERIOLOGr. 



perature as 18° C. From 42° C. on the development is 

 checked. 



Under most favorable conditions the growth is very 

 slow. It grows as well without as with oxygen. It 

 is, therefore, one of the facultative anaerobic forms. 



The most successful efforts at the cultivation of this 

 organism are those seen when the agar-gelatin mixture 

 of Guarniari is employed. (See this medium.) 



It may be stained with the ordinary aniline staining 

 reagents. For demonstration of the capsule the method 

 of Gram gives the best results. (See Stainings.) 



This organism is conspicuous for the irregularity of 

 its behavior when grown under artificial conditions ; 

 usually it loses its pathogenic properties after a few 

 generations ; but again this peculiarity may be retained 

 for a much longer time. Not rarely it fails to grow 

 after three or four transplantations on artificial media, 

 though at times it may be carried through many gen- 

 erations. 



Inoculation into animals. The results of inocula- 

 tions with pure cultures of this organism are also 

 conspicuous for their irregularity. Most commonly 

 when the organism is of full virulence the form of 

 septicsemia just described is produced, but at times 

 it is found to be totally devoid of pathogenic powers; 

 between these extremes cultures may be obtained pos- 

 sessing all variations in the intensity of their disease- 

 producing properties. The principal pathological con- 

 ditions that may be produced by this organism by 

 inoculations into animals, according to the degree of 

 its virulence, are acute septicsemia, spreading inflam- 

 matory exudations, and circumscribed abscesses. All 

 three of these conditions may sometimes be produced 



