42 ORDER I. PSEUDOMONADALES 



The type species is Thiodictyon elegans Winogradsky. 



1. Thiodictyon elegans Winogradsky, Issatchenko (Etudes niicrobiologiques des 



1888. (Schwefelbacterien, Leipzig, 1888, 80.) Lacs de Boue, Leningrad, 1927, 113-114) 



e'le.gans. L. adj. elegans choice, elegant. recognizes a forma vmius and a forma 



Rods 1.5 to 1.7 by 2.5 to 5 microns; or ^agna, differentiated mainly by the size of 



longer just prior to cell division. Usually 

 contain a large pseudovacuole (aerosome), 

 leaving a rather thin protoplasmic sheath 

 along the cell wall 



the individual rods. 



Habitat: Mud and stagnant water con- 

 taining hj^drogen sulfide and exposed to 



Sulfur droplets generally quite small; light; sulfur springs, 

 deposited exclusively in the thin proto- Illustrations: Winogradsky, ioc. ci<., Plate 



plasmic layer. Ill, fig. 13-17. 



Genus V. Thiothece Winogradsky, 1888. 



(Schwefelbacterien, Leipzig, 1888, 82.) 



Thi.o.the'ce Gr. noun thium sulfur; Gr. noun thece a box, chest; M.L. fem.n. Thiothece 

 sulfur box. 



Sulfur purple bacteria which, in their growth characteristics, resemble the blue-green 

 alga Aphanothece. Cells spherical to relatively long cylindrical-ellipsoidal, embedded in a 

 gelatinous capsule of considerable dimensions. Following cell division the daughter cells 

 continue to secrete mucus which causes the individual bacteria to remain clearly separated 

 by an appreciable distance; the common capsule thus appears only loosely filled. The cells 

 may become actively motile and separate themselves from the colony. Such swarmers 

 closely resemble the cells of certain species of Chromatium. Contain bacteriochlorphyll 

 and carotenoid pigments. Capable of photosynthesis in the presence of hydrogen sulfide, 

 producing elemental sulfur as an intermediate oxidation product which is stored as sulfur 

 globules inside the cells. 



The type species is Thiothece gelatinosa Winogradsky. 



1. Thiothece gelatinosa Winogradsky, in outermost layers of protoplasm and 

 1888. (Schwefelbacterien, Leipzig, 1888. 82.) generally small. 



ge. la. ti. no'sa. L. part. adj. gre/aiMS frozen. Habitat: Mud and stagnant water con- 



stiffened; M.L. noun ffeZafznum gelatin, that taining hydrogen sulfide and exposed to 

 which stiffens; M.L. adj. gelatinosus gelati- jj^^^. ^^^^^^ springs. 



Illustrations: Winogradsky, lac. cit., PI. 



nous. 



Cells 4 to 6 by 4 to 7 microns, spherical 

 to cylindrical. Color of individual cells, 

 faint, often grayish violet or even dirty Univ. Tokyo, Japan, 10, 1897, 170, PI. XIV 



III, fig. 9-12; Miyoshi, Jour. Coll. Sci., Imp. 



Univ. r 



yellowish. Sulfur globules usually deposited fig. 25. 



Genus VI. Thiocystis Winogradsky, 1888. 



(Schwefelbacterien, Leipzig, 1888, 60.) 



Thi.o.cys'tis. Gr. noun thium sulfur; Gr. noun cystis the bladder, a bag; M.L. fem.n. 

 Thiocystis sulfur bag. 



Sulfur purple bacteria which form compact colonies, many of which may be loosely em- 

 bedded in a common gelatinous capsule. Individual cells spherical to ovoid, often diplo- 

 coccus-shaped. Colonies may emerge as more or less large units from out of the common 

 capsule and break up afterwards, sometimes into single swarmers; or the aggregates may 

 split up inside the original capsule and release small motile units or single swarmers. In 

 pure cultures frequently develop as single cells and diplococci. Produce bacteriochlorophyll 



