318 MICROBIOLOGY 



agar cultures it is from 1.2 to 1.8 /* long and from 0.5 to 0.8 p 

 broad. The ends are rounded. Spores have not been ob- 

 jserved. It is actively motile and a variable Dumber, but 

 usually from 3 to 5, flagella have been demonstrated. The 

 length of the flagella also vary. The average seems to be 

 about 7 /*, although filaments 55 /* with an average length of 

 35 to 40 /JL are reported. 12 



Staining 1 . It stains readily with the, aniline dyes. 

 Preparations made from cultures usually stain uniformly ; 

 while in the preparations made from the tissue of inoculated 

 animals there is frequently exhibited a light center with a 

 deeply stained periphery. It is Gram negative. 



Cultivation. This bacillus grows readily on all of the 

 ordinary media used in bacteriological work at a temperature 

 of 30 to 38 C. 



Agar. On the surface of inclined agar after 24 hours at 

 a temperature of 37 C. a grayish, glistening non viscid 

 growth appears. "When isolated the colonies are nearly round, 

 convex, 0.5 to 2.0 mm. in diameter. The edges are sharply 

 defined and even. In stab cultures a grayish growth develops 

 along the needle track with a more vigorous growth on the 

 surface about the needle puncture. The growth reaches its 

 maximum in about 48 hours. 



Gelatin. In this medium the growth is moderately 

 feeble, the colonies appearing as grayish dots. When magni- 

 fied they are finely granular and of a yellowish tint. The 

 quantity and form of growth depends considerably upon the 

 reaction of the gelatin. If decidedly alkaline there is often 

 a tendency for the growth to spread. There is no softening 

 or liquefaction of the medium. 



Potato. The growth on potato takes the form of a very 

 thin glistening layer. It is usually of a faintly yellowish color 

 but this is subject to variation on different potatoes. If the 

 reaction is strongly acid no growth appears. 



Bouillon. In alkaline bouillon it imparts in 24 hours a 



12 Ferrier. Archives de Med. Exper. et d'Anat. Patholog., Vol. 

 VIII (1895) p. 58. 



