GENUS BACTERIUM 267 



in pairs. Spherical forms are numerous in actively growing- 

 cultures. The size varies from 0.5 to 0.7 /A in width and from 

 1 to 2 /A in length. A bipolar arrangement of the protoplasm 

 is demonstrated when carbol fuchsin and alkaline methylene 

 blue stains are used. The bipolar staining is more noticeable 

 in smear preparations from tissues. The presence of a capsule 

 is suggested by an unstained area surrounding each organism 

 in smear preparations from tissues, especially the blood. 



Staining. It stains readily with the aniline dyes. It is 

 Grain negative. 



Cultivation. This organism grows readily on alkaline 

 agar or in bouillon made from meat. 



Agar. The colonies on agar, after forty-eight hours at 

 37.5 C. appear as round, smooth, thin, shiny disks, with en- 

 tire border and measuring about 2 mm. in diameter. Under 

 a two-thirds objective they appear coarsely granular and show 

 concentric circular markings. They appear smoky brown in 

 color by transmitted light, and gray by reflected light. Colo- 

 nies beneath the surface are usually lenticular in shape, and 

 the granular appearance is more marked under a two-thirds 

 objective than in the surface colonies. After twenty-four 

 hours the growth on slant agar is flat, smooth, shining, grayish 

 white by reflected light, and smoky brown by transmitted 

 light. The condensation water becomes decidedly turbid. 

 Growth upon glycerin agar presents no features distinguish- 

 able from that on agar slant. 



Potato. No visible growth has been observed. Migula 

 describes a feeble growth after some days. 



Dog blood serum. After twenty-four hours at 37.5 C. 

 the path of the needle is covered with a smooth, shiny, raised 

 growth. The condensation water is markedly turbid. 



Bouillon. In from 24 to 48 hours the fluid becomes 

 slightly clouded and does not clear up on standing. In young 

 cultures no sediment is deposited, but in older cultures a vis- 

 cous sediment accumulates. The reaction is alkaline to litmus 

 and markedly so in old cultures. No pellicle is formed, but 

 occasionally a circular bluish band of growth adheres to the 



