274 



HARDWICKE'S SCIENCE-GOSSIP. 



L 



NOTES ON THE SCHIZOMYCETES. 



\Cotttinuedfrom page ■zid.l 



No. IV.— VII. 



EPTOTHRIX, Kiitzing. Threads very long 

 and slender, unhranchcd, apparently inarticulate, 

 colourless, loithout motion, fiot granular, free or 

 felted together. 



The fungi assigned to the genus Leptothrix are of 

 very questionable value as species ; I therefore 

 include the following with all resei-ve. Leptothrix- 

 like formations are very common in Bacillus. 



Since this genus will probably remain only a short time among 

 the fungi, I do not think it desirable to give it a new name now. 

 The greater part of the species of Leptothrix are typical phyco- 

 ehromaceous algae ! 



VIII. Beggiatoa, Trevisan. Threads very long, 

 but thicker than in Leptothrix, for the most part in- 

 distinctly jointed, stiff", but actively oscillating, em- 

 bedded in gelatine, colourless ; protoplasm provided 

 with numerous, strongly refringent gramiles, which 

 consist of sulphur. 



The genus Beggiatoa is easily to be recognised by 

 the strongly motile threads, which form usually chalk- 

 wliite or slimy masses, and in which the articulations 

 cannot, as a rule, be perceived without further treat- 

 ment. 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 



Fig. 213. — Sarcina hyalina, X 420 

 (after Kiitzing). 



Fig. 212. — Threads of 

 Leptothrix, X 800 

 (after Rabenhorst). 



Fig. 111,.— Beggiatoa pdlucida, X 400 (after Cohn). 



39. L. bticcalis, Robin, 



Threads very long and slender, 7-1 /x (seldom 

 somewhat more) thick, inarticulate, colourless, 

 densely felted in white masses. 



Mixed with Micrococci (usually also with Vibrio) 

 in the white slime of the teeth, on the epithelium of 

 the mouth, and in hollow teeth ; probably the cause 

 of dental caries. 



The seat of this fungus is especially in the canals of the 

 dentine, yet it also attacks the substance of the enamel, which 

 it destroys by degrees. In those canals the fungus produces 

 decided enlargeihents, and afterwards their walls become 

 pierced by crevices and fissures, and break to pieces. 



40. L. parasitica, Kiitz. 



Threads very slender, for the most part curled and 

 crisped, indistinctly jointed, loosely felted, almost 

 colourless, about i ^ thick, 100-140 ^ long. 



Parasitic on Scytonemacex and other allied algse. 



Perhaps also Leptothrix ptisilla, Rabenhorst, and L. lanugo, 

 Kiitz., should be placed among the fungi. 



Fig. 215. — a, Beggiatoa alba, X 600 ; b, B. nivea, with 

 the plasma contracted, X 900; c, B. leptojnitiforviis, 

 X 800; d, B. iigrina, X 800 {a, c, and d, after Kiitzing; 

 b, after Rabenhorst). 



sulphuretted 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. 



41. B. alba (Vauch.), Trev. 



Beggiatoa punctata, Trev. 

 Oscillaria alba, Vauch. 

 Hygrocrocis Vandelli, Menegh.' 

 Threads without distinct articulations, forming 

 dirty or chalk-white gelatinous masses, 3-3^ jj. thick. 

 In sulphur springs and marshes. 

 Var. marina, Cohn. Threads densely filled with 

 blackish granules, only 2 fn thick. 



Forming a delicate snow-white gelatinous mem- 

 brane on decaying animals and algse in an aquarium 

 with sea-water, (Fig. 215, a.) 



