1000 



MANUAL OF DETERMINATIVE BACTERIOLOGY 



As iu the case of Achromatium , it is difficult to establish distinct species. Those 

 that have been described differ only in size, and the differences appear to be far from 

 constant. For Thiovulnm {Monas) mulleri (Warming) Lauterborn (Verhandl. 

 Naturhist.-medizin. Vereins, Heidelberg, N. F., 13, 1915, 414) the diameter is stated 

 by Warming (Videnskab. Meddel. naturhistor. Foren., Kjobenhavn, 1875, No. 20-28, 

 363), Hinze (Ber. d. deut. bot. Ges., 31, 1913, 191) and Lauterborn {loc. cit., 415) 

 respectively to be 5.6 to 15, 13 to 15 and 5 to 13 microns. The ovoid cells of Thiovuhnn 

 majus are noted as being 11 to 18 microns long and 9 to 17 microns wide, while Thio- 

 vuluni viinus comprises the smaller forms from 9.6 to 11 microns long by 7.2 to 9 

 microns wide. In view of the regular occurrence of nil intermediate sizes it seems 

 best to recognize only a single species at present. 



1. Thiovulum majus Hinze. (Hinze, 

 Ber. d. deut. bot. Ges., 31, 1913, 195; in- 

 cluding Thiovulum yninus Hinze, idem.; 

 Monas mulleri Warming, Videnskab. 

 Meddel. naturhistor. Foren., Kjoben- 

 havn, 1875, No. 20-28, 363; Achromatium 

 mulleri Migula, Syst. d. Bakt. 2, 1900, 

 1038; Thiovulum mulleri Lauterborn, 

 Verhandl. Naturhist.-medizin. Vereins, 

 Heidelberg, N.F., 13, 1915, 414.) From 

 Latin major, large. 



Unicellular organisms, spherical to 

 ovoid. Cytoplasm often concentrated 

 at one end of the cell, the remainder 

 being occupied by a vacuole. Multipli- 

 cation by constriction which, in late 

 stages, merges into fission. Size of cells, 

 5 to 20 microns in diameter. 



The most characteristic feature is its 

 motility; it is the only one of the spheri- 

 cal to ovoid, colorless sulfur bacteria 

 capable of rapid movement. Flagella- 

 tion has not been definitively demon- 

 strated, but the type of locomotion sug- 

 gests the presence of polar flagella. 



Normally contains sulfur droplets in 

 cytoplasm, frequently concentrated at 

 one end of cell. 



Microaerophilic; apparently requires 

 hydrogen sulfide. 



Habitat : In sulfide-containing water, 

 usualljr accumulating near the surface. 

 Often in cultures of decaying algae. 

 Both in fresh water and marine environ- 

 ments. 



Germs HI. Macromonas Uiermohl and Koppe. 



(Verhandl. Intern. Ver. f. Theoret. u. angew. Limnologie, 1923, 86.) From Latin 

 macro, large and monas, a unit or cell. 



Colorless, cylindrical to bean-shaped bacteria, actively motile by means of a 

 single polar flagellum. Multiplication by constriction (fission). Chiefly character- 

 ized by the occurrence of calcium carbonate inclusions in the form of large spherules. 

 In their natural habitat they may also contain small sulfur globules. 



The type species is Macromonas mobilis (Lauterborn) Utermohl and Koppe. 



Two species have primarily been distinguished on the basis of cell size. Whether 

 this is sufficiently constant to serve as a specific character has not been definitely 

 established. From studies still limited in scope and extent on the organisms in their 

 natural habitat, it appears at present that the two species should be maintained, at 

 least provisionally. It is possible, however, that further observations, especially 

 with cultures under different environmental conditions, will show the occurrence of 

 intermediate types and of a greater range of variation in size of pure cultures than 

 what has previously been reported. 



