Beggiatoa. 



37 



Var. marina, Cohn (B. CErstedtii, Rabenhorst). 

 Threads densely filled with blackish granules, only 2 ft 

 thick. 



Fig. 29. a, Beggiatoa alia, X 600 ; b, B. nivea, with the 

 plasma contracted, X 900 ; c, B. leptomitiformis, X 800 ; 

 d, B. tigrina, X 800 (a, c, and d, after Kutzing ; *, after 

 Rabenhorst). The engraver has made these threads too 

 thick, especially c. 



Forming a delicate snow- 

 white gelatinous membrane on 

 decaying animals and Algae in an 

 aquarium with sea-water. (Fig. 

 30.) 



Fig. 30. Beggiatoa alba, var. ma- 

 rina, X 660 (after Warming). 



51. B. nivea, Rabenhorst (" Flor. Eur. Alg.," ii. p. 94). 

 Leptonema niveum, Rabenhorst 



Threads very slender, indistinctly jointed, i-i '5 fi thick 

 (according to Rabenhorst), forming undulated woolly tufts 

 of a chalk-white colour. (Fig. 29^.) 



