324 BACTERIOLOGY, 



Genus II. Beggiatoa. 



SPECIES. 



UNASSOCIATED WITH DISEASE : 



Beggiatoa alba .... Simple saprophyte. 

 Beggiatoa mirabilis . . . 



Beggiatoa roseopersicina . . Chromogenic saprophyte. 



Beggiatoa alba, Vauch. Cocci, rods, spirals, 

 and threads (Fig. 1 26). The threads are longer and 

 thicker than leptothrix, indistinctly articulated, 

 actively oscillating, and colourless ; their protoplasm 

 contains numerous strongly refractive granules 

 consisting of sulphur. They occur as greyish- or 

 chalk- white gelatinous threads, 3 3*5 p, thick, in 

 sulphur springs and marshes. 



Beggiatoa mirabilis, Cohn. Threads dis- 

 tinguished from others of this genus by their 

 breadth, which may reach 30 /A. They are motile, 

 bent and curled in various ways, and rounded at 

 the ends. Around the threads isolated cells have 

 been observed, " macrococci," but spiral forms are 

 as yet unknown. The threads are filled with 

 sulphur granules. They occur on sea water, form- 

 ing a white gelatinous scum on decomposing 

 algae, etc. 



METHODS OF EXAMINING SPECIES OF BEGGIATOA. 



The articulation of the threads is best demonstrated 

 by staining with an alcoholic solution of methyl-violet, 

 fuchsine, or vesuvin ; or by treating with sodic sulphate, 

 or warm glycerine. 



