Spirillum Rubrum, Esmarch. 



ORIGIN. From the putrefied cadaver of a mouse. 



FORM. Clear, transparent, thick cells, which are 

 usually single, appearing- as larg-e bent rods or comma 

 bacilli (vibrio). It may form spirals of three or four, or 

 even forty windings. Involution forms are common in old 

 cultures. 



MOTILITY. It is actively motile. Each end of a spiral 

 has one wavy nag^ellum. 



SPORULATION. True spores have not been observed. 



ANILIN DYES. These stain slowly but well, especially 

 if the dye is slightly warmed. 



GROWTH. This is extremely slow. 



Gelatin plates. Owing to the very slow development of colonies 

 ordinary plates cannot be used. In roll-tubes, colonies develop in from 

 seven to ten days, and at first are minute and grayish; later the cen- 

 ter of each colony becomes tinged with pink and eventually becomes 

 red. The edge is smooth and the contents are finely granular. 



Stab culture. This is the most characteristic. Growth takes 

 place along the entire line of inoculation, forming a row of colonies. 

 The growth spreads slightly on the surface, and is colored a light 

 pink. The pigment formation is most marked along the line of punc- 

 ture where oxygen is absent. It passes through a light pink to a 

 beautiful dark wine-red color. Ordinary bacterial pigments are 

 formed only in the presence of air, and are secondary products, 

 whereas this pigment is formed in the absence of air and is, there- 

 fore, a primary product. 



Streak culture. On agar, it forms moist, thick, non-spreading 

 patches, which, when old, possess a light pink or red color, especially 

 near the center. On potato, it develops slowly, forming minute 

 deep red colonies. On blood-serum, the growth is much the same as 

 on agar. 



Milk. In fluid media, milk, bouillon, etc., it forms long spirals 

 which show little or no motion. 



OXYGEN REQUIREMENTS. It is a facultative anaerobe. 

 TEMPERATURE. It grows between 16 and 40. The 

 optimum temperature is about 37. 



BEHAVIOR TO GELATIN. It does not liquefy. 



PATHOGENESIS. It has no effect on animals. 



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