DESCRIPTION OF SPECIES. 



543 



vesicles, dark granules are to be 

 seen, which consist of sulphur. 

 The micro-organisms occur on the 

 surface of marshes, or on water in 

 which-- 1 algge are rotting. They 

 form a rose-red, blood-red, violet- 

 red, or violet-brown scum ; and 

 sometimes in such quantity that 



Cladothrix dichotoma (Cohn). 

 Threads resembling those of lep- 

 tothrix ; slender, colourless, not 

 articulated, straight or slightly 

 undulated, and in places twisted 

 in irregular spirals with pseudo- 

 branchings. The development can 

 be traced from the cocci to rods and 



FIG. 215. BEGGIATOA ALBA. 



A. Threads at base distinctly linked, partly spiral. B. A -thread, spiral in its 

 whole length. C, D. Fragments detached from threads ; immotile. E. Active 

 spirillum-forms, with a flagellum at either end. F, G. Thin and short spiral 

 forms. H. A spiral showing the individual links, x 540 (Zopf). 



whole marshes and ponds may be 

 coloured blood-red by them. 



Spirillum sanguineum, rosaceum, 

 violaceum, monas vinosa and Okenii, 

 and Rhabdomonas rosea are pos- 

 sibly phase-forms of Beggiatoa 

 roseo-persicina. 



threads. The latter are at the 

 beginning simple threads, which 

 were formerly described as Lepto- 

 thrix parasitica, or, if coloured by 

 impregnation with iron, as Lepto- 

 thrix ochracea. Later they form 

 false branches by single rods turning 



