FAMILY ACHROMATIACEAE 



1001 



Kc;/ to the species of genus Macromonas. 



I. Cells measuring 12 niifrons or more in length and 8 microns or more in width. 



1. Macromonas niobilis. 



II. Cells measuring less than 12 microns in length and 5 microns or less in width. 



2. Macromonas hipunctata. 



1. Macromonas mobilis (Lauterborn) 

 Utermohl and Koppe. {Achromatium) 

 mobi e Lauterborn, Verhandl. Xatur- 

 hist.-Medizin. ^'ereins, Heidelberg, X.F., 

 13, 1915, 413; Microspira vacillans Gickl- 

 horn, Cent. f. Bakt., II Abt.,, 50, 1920, 

 422; Utermohl and Koppe, A'erhandl. 

 Intern. Ver. f. theoret. u. angew. Lim- 

 nologie, 1923, 86 and Utermohl and 

 Koppe, Arch. f. Hj'drobioL, Suppl. Bd. 5. 

 1925, 234.) 



Colorless sulfur bacteria, always oc- 

 curring sing!}', slightly curved, elongated 

 ellipsoids or cjdinders with broad hemi- 

 spherical ends. Length varies from 12 

 to 30 microns, width from 8 to 14 microns; 

 most common size 20 by 9 microns. INIul- 

 tiplication by constriction in the middle. 



Cells actively motile by means of a 

 single polar fiagellum, distinctly visible 

 without special staining. It is 20 to 40 

 microns long, and, with respect to the 

 direction of motion, alwaj's posteriorly 

 placed. Rate of movement somewhat 

 sluggish, about 800 microns per minute, 

 probably on account of high specific 

 gravity of cells. 



Normally contain small sulfur droplets 

 and, in addition, large, roughly spheri- 

 cal inclusions of calcium carbonate. 

 Two to four such crystal masses almost 

 fill a single cell. Under unfavorable 

 conditions the calcium carbonate crys- 

 tals may disappear before the sulfur 

 globules. 



Microaerophilic; apparently require 

 hydrogen sulfide. 



Habitat: Fresh water environment 

 containing sulfide and calcium ions; in 

 shallow basins and streams in the upper 

 layers of the mud. 



2. Macromonas bipunctata (Gicklhorn) 



Utermohl and Koppe. {Pseudomonas 

 bipunctata Gicklhorn, Cent. f. Bakt., II 

 Abt., 50, 1920, 425; Utermohl and Koppe, 

 Arch. f. Hydrobiol., Suppl. Bd. 5, 1925, 

 235.) 



Cells colorless, occurring singly, cylin- 

 drical with hemispherical ends; after 

 cell division often temporarily pear- 

 shaped. Length S to 12 microns, width 

 3 to 5 microns. ^Multiplication by con- 

 striction in the middle. 



Actively motile b}' means of a single 

 polar flagellum, about 10 to 15 microns 

 long, and always posteriorly placed 

 with respect to the direction of move- 

 ment. Flagellum delicate, not visible 

 without staining. Kate of movement 

 sluggish, about 600 microns per minute. 

 Probably this slow motion is on account 

 of the high specific gravity of the cells. 



Xormally contain calcium carbonate 

 crystals as inclusions. These are in the 

 form of large spherules, one or two of 

 which nearly fill the individual cells. 

 Sulfur globules have not been demon- 

 strated with certainty as yet. 



Microaerophilic, but it is uncertain 

 whether hydrogen sulfide is required. 



Source: From stems, leaves, etc. of 

 fresh water plants in ponds near Graz, 

 Austria. 



Habitat : Fresh water environments 

 containing calcium ions; but it has been 

 found in sulfide-containing as well as in 

 sulfide -free water. In shallow basins 

 and streams in upper layers of the mud. 



Note: Another species in this genus is 

 Macromonas hyalina (Gicklhorn) Uter- 

 mohl and Koppe. (Pseudomonas hyalina 

 Gicklhorn, Cent. f. Bakt., II Abt., 50, 

 1920, 426; Utermohl and Koppe, Arch. f. 

 Hydrobiol., Suppl., 5, 1925,235.) Similiar 

 to Macromonas bipunctata. 



