40 



ORDER I. PSEUDOMONADALES 



earotenoid pigments, hence, pigmented purplish to red. Capable of carrying out a photo- 

 sj'nthetic metabolism in the presence of hydrogen sulfide, cells then storing sulfur globules. 

 Anaerobic. 



The type species is Thiosarcina rosea (Schroeter) Winogradsky. 



1. Thiosarcina rosea (Schroeter, 1886) 

 Winogradsky, 1888. (Sarcina rosea Schroeter , 

 Kryptog. -Flora von Schlesien, 3, 1, 1886, 154; 

 Winogradsky, Zur Morphologie und Physio- 

 logic der Schwefelbacterien, Leipzig, 1888, 

 104.) 



ro'se.a. L. adj. roseus rosy, rose-colored. 



Cells spherical, 2 to 3 microns in diameter, 

 occurring in packets containing 8 to 64 cells. 

 Infrequently motile. Color ranging from 

 purplish rose to nearly black. 



Anaerobic. 



Habitat : Occur less frequently than other 

 sulfur purple bacteria; probably widely dis- 

 tributed in mud and stagnant bodies of 

 water containing hydrogen sulfide and ex- 

 posed to light; sulfur springs. 



Illustration: Issatchenko, Recherches sur 

 les microbes de I'ocean glacial arctique, 

 Petrograd, 1914, Plate II, fig. 5. 



Genus II. Thiopedia Winogradsky , 1888. 



(Zur Morphologie und Physiologie der Bacterien, I. Schwefelbacterien, Leipzig, 18S8, 85.) 



Thi.o.pe'di.a. Gr.n. thium sulfur; Gr.n. pedium a plain, a flat area; M.L. fem.n. Thio- 

 pedia a sulfur plain. 



Individual cells spherical to short rod-shaped, the latter shortly before cell division. 

 Arranged in flat sheets with typical tetrads as the structural units. These arise from divi- 

 sions of the cells in two perpendicular directions. Cell aggregates of various sizes, ranging 

 from single tetrads to large sheets composed of thousands of cells. Non-motile. Non-spore- 

 forming. Contain bacteriochlorophyll and earotenoid pigments. Capable of photosynthesis 

 in the presence of hydrogen sulfide, then storing sulfur globules. Anaerobic. 



The type species is Thiopedia rosea Winogradsky. 



1. Thiopedia rosea Winogradsky, 1888. 

 (Erythroconis littoralis Oersted, Naturhist. 

 Tidsskrift, 3, 1840-1841, 555; Winogradsky, 

 Zur Morphologie und Physiologie der 

 Schwefelbacterien, Leipzig, 1888, 85.) 



ro'se.a. L. adj. roseus rosy, rose-colored. 



Cells 1 to 2 microns, often appearing as 

 slightly elongated cocci regularly arranged 

 in platelets. 



Color, pale red to nearly black, depending 

 upon the amount of sulfur stored. Red color 

 visible only with large cell masses, not in 

 individuals. 



According to Winogradsky, the cells are 

 often embedded in a common slime capsule; 

 the e.xtensive studies of Utermohl (Archiv f . 

 Hydrobiol., Suppl. Vol. 5, 1925, 251-276) 

 make the regular occurrence of such cap- 

 sules extremely doubtful. On the other 

 hand, Utermohl emphasizes as quite charac- 



teristic the common presence of a relatively 

 large pseudovacuole, or aerosome, in the 

 cells of this species encountered in plankton 

 samples. Winogradskj^ does not mention 

 this; nevei-theless, it appears to be a regular 

 and valuable distinguishing feature. 



Anaerobic. 



Habitat: Widely distributed in mud and 

 stagnant bodies of fresh, brackish and salt 

 water containing hydrogen sulfide and ex- 

 posed to light; sulfur springs. Common, 

 frequently giving rise to very extensive 

 mass developments. 



Illustrations: Warming, Videnskab. 

 Meddel. naturhist. Forening, Kjobenhavn, 

 1876, Plate VIII, fig. 2; Winogradsky, op. 

 cit., 1888, 85, Plate III, fig. 18; Pringsheim, 

 Naturwissensch., £0, 1932, 481, the last one 

 a truly excellent photomicrograph. 



