36 Synopsis of the Bacteria and Yeast Fungi. 



IX. BEGGIATOA, Trevisan (" Prospetto della Flora 

 Euganea," p. 76). 



Threads very long, but thicker than in Leptothrix, for 

 the most part indistinctly jointed, rigid, but actively oscillating, 

 embedded in gelatine, colourless ; protoplasm provided with 

 numerous, strongly refringent granules, which consist of 

 sulphur. 



The genus Beggiatoa is easily to be recognised by the 

 strongly motile threads, which form usually chalk-white 

 or slimy masses, and in which the articulations cannot, as 

 a rule, be perceived without further treatment. In order 

 to see them, allow the threads to dry on the slide, and then 

 add sulphide of carbon, which by degrees dissolves the 

 sulphur granules which in the living Fungus obscure the 

 joints. The Beggiatose live for the most part in sulphur 

 hot-springs, where they decompose the compounds of 

 sulphur dissolved in the water, and eliminate free sul- 

 phuretted hydrogen. So that such water, enclosed in a 

 flask with Beggiatoa, evolves an intense smell of sulphuretted 

 hydrogen. 



The accepted species of Beggiatoa are of very doubtful value ; they 

 are discriminated almost entirely by the thickness of the threads. 



50. B. alba (Vaucher), Trevisan (" Nomencl.," p. 58). 

 Beggiatoa punctata, Trevisan. 

 Oscillaria alba, Vaucher. 

 Hygrocrocis Vandelli, Meneghini. 



Threads without distinct articulations, forming dirty 

 or chalk-white gelatinous masses, 3-3 -5 p. thick. (Fig. 

 290.) 



In sulphur springs and marshes. 



