SPIRILLUM NIGRUM 577 



remains alive for 20-25 days : it produces no gas but gives off a disagreeable 

 smell. 



Isolation. Lewkowicz isolates the bacillus in Veillon's tubes containing 

 glucose agar to which one-third its volume of the peritoneal fluid of a child 

 is added. After incubating at 37 C. for 4 days sub-cultures can be sown in 

 glucose-agar or glucose-broth to both of which it is necessary to add some 

 serous fluid. 



Ellermann recommends the following method for the purpose of isolating 

 the bacillus from the mouths of healthy persons : 



1. Sow some dental tartar in Cibil's broth and incubate at 37 C. : after 

 2 days a deposit will have formed consisting of cocci and the Bacillus 

 fusiformis. 



2. At the same time sow a tube of sloped agar freely with dental tartar ; 

 then sow a tube of broth with the growth obtained (staphylococci and strepto- 

 cocci). 



3. Sterilize the aerobic broth culture, decant the broth and sow it anaerobi- 

 cally with the impure culture in Cibil's broth : the medium is exhausted for 

 the cocci, and the fusiform bacillus grows abundantly in pure culture. After 

 sowing a few sub-cultures anaerobically on serum-agar a pure culture of the 

 Bacillus fusiformis is obtained. 



Glucose-serum-agar. (a) Stab culture. Deep stab cultures in glucose- 

 serum-agar give rise, after incubating for 3 or 4 days, to a minimal growth 

 consisting of a greyish streak which extends to within 1 cm. of the surface 

 of the agar (Lewkowicz). 



(f3) Isolated colonies. Veillon's tubes. After incubating for 24-48 hours 

 small, delicate, opaque colonies appear, greyish or yellowish-white in colour 

 with a deeper coloured centre : on further incubation (a fortnight or 3 weeks) 

 the colonies may attain a diameter of 2 mm. (Miihlens, Ellermann). 



(7) Plates. When sown in vacuo on the surface of glucose-agar containing 

 an albuminous fluid the Bacillus fusiformis grows as small grey points, trans- 

 lucent and thin, which may reach a diameter of 1'25 mm. and which show 

 under the microscope a very delicate festooned margin (Lewkowicz). 



Broth. In glucose-broth containing a serous fluid, after incubating for a 

 few days, the bacillus produces a somewhat abundant greyish white deposit, 

 the broth remaining clear (Lewkowicz). 



VIII. SPIRILLUM NIGRUM. 



The Spirillum nigrum was described by Rist in 





suppurations of the ear. 



Guinea-pigs are the most susceptible animals, , / , 

 but the pathogenic properties of the organism \ >, 

 for the lower animals are very slight. 



Microscopical appearance. The Spirillum ni- _-^\o 



grum is a small, very slender organism of the 

 shape of a parenthesis or an S ; its ends are ^ /"* 



rounded and it is marked by a small black point FIG. 272. Spirillum nigrum. 

 either in the centre or at one of the ends. It is gft,^ an x ag iooo culture ' Car " 

 highly motile. 



Staining reactions. The Spirillum nigrum stains with considerable diffi- 

 culty ; the only satisfactory dye is carbol-fuchsin without heat. The spirilla 

 stain bright red and present a granular appearance. 



The organism is gram-negative. 



Cultural characteristics. The Spirillum nigrum is a strictly anaerobic 



2o 



