64 



ORDER I. PSEUDOMONADALES 



may be found as elements in chains for the 

 greater part composed of normal individ- 

 uals. 



Habitat: Mud and stagnant water con- 

 taining rather high concentrations of hy- 

 drogen sulfide and exposed to light; sulfur 

 springs. 



Illustrations: Szafer, op. cit., 1910, PI. 

 VI, fig. 5; Perfiliev, Jour. Microbiol. (Rus- 

 sian), 1, 1914, PI. II, fig. 1, 5-12; Lauter- 

 born, op. cit., 1915, PI. Ill, fig. 33. 



2. Pelodictyon aggregatuin Perfiliev, 

 1914. (Aphanothece luteola Schmidle, Bei- 

 hefte Botan. Cent., 10, 1901, 179; Perfiliev, 

 Jour. Microbiol. (Russian), 1, 1914, 197.) 



ag.gre.ga'tum. L. part. adj. aggregatus 

 added to a flock, aggregated, clumped. 



Cells usually rod-shaped, about 1 to 1.5 

 by 2 to 4 microns, often vacuolated, produc- 

 ing slime capsules and united into irregu- 

 larly shaped, three-dimensional colonies in 

 which the cells are more or less tightly 

 packed without orderly arrangement. Colo- 

 nies may attain a size of up to 1 mm; fre- 

 quently they are not fully compact but 

 contain less dense areas or appear perfo- 

 rated, thus forming transition stages to 

 Pelodictyon claihratiforme. Non-motile. 



Color: Yellowish green. 



Abnormal cell forms (involution forms) 

 usually in the shape of elongated and 

 curved, forked or club-shaped and swollen 

 rods, occasionally suggesting branching at 

 extremities. 



Source: Isolated from sulfureted water in 

 Europe ; also reported by Button and Juday 



(Ecology, 25, 1944, 277) from Scaffold Lake, 

 Wisconsin. 



Habitat: Mud and stagnant water con- 

 taining rather high concentrations of hydro- 

 gen sulfide and exposed to light; sulfur 

 springs. 



Illustrations: Perfiliev, ibid., PI. II, fig. 

 2; Lauterborn, Verhandl. naturhistor.- 

 medizin. Vereins, Heidelberg, N.F. 13, 1915, 

 PI. Ill, fig. 29-31. 



3. Pelodictyon parallelum (Szafer, 

 1910) Perfiliev, 1914. (Aphanothece parallela 

 Szafer, Bull. Acad. Sci., Cracovie, Ser. B, 3, 

 1910, 163; Perfiliev, Jour. Microbiol. (Rus- 

 sian), 1, 1914, 198.) 



pa.ral.le'lum. Gr. adj. parallelus parallel. 



Cells rather small, spherical to ovoid, or 

 even rod-shaped; about 0.5 to 1 by 1 to 3 

 microns, occurring in chains and forming 

 flat, plate-like, two-dimensional aggre- 

 gates in which the chains are arranged as 

 parallel strands. Non-motile. 



Color: Yellowish green. 



Abnormal cell forms not specifically men- 

 tioned, but likely to occur and to resemble 

 those of other species. 



This species may well be a special growth- 

 form of Chlorobium limicola. 



Habitat: Mud and stagnant water con- 

 taining rather high concentrations of hydro- 

 gen sulfide and exposed to light; sulfur 

 springs. 



Illustrations: Szafer, op. cit., 1910, PI. 

 VI, fig. 7; Perfiliev, op. cit., 1914, PI. II, fig. 

 2. 



Genus HI. Clathrochloris Geitler, 1925. 



(Geitler, in Pascher, Die Siisswasserflora Deutschlands, Osterreichs und der Schweiz, 

 Jena, 12, 1925, 457.) 



Clath.ro. chlo'ris. L. pi. noun clathri lattice; Gr. adj. chlorus green; M.L. fem.n. Clathro- 

 chloris green lattice. 



Sulfur green bacteria of small size, generally spherical and arranged in chains which are 

 united into loose, trellis-shaped aggregates, somewhat similar to those of Pelodictyon cla- 

 thratiforme and Pelodictyon aggregatum. Cells usually contain sulfur globules. Color is yel- 

 loivish green. Non-motile. 



The type species is Clathrochloris sulphurica (Szafer) Geitler. 



1. Clathrochloris sulphurica (Szafer, 

 1910) Geitler, 1925. {Aphanothece sulphurica 

 Szafer, Bull. Acad. Sci., Cracovie, Ser. B, 3, 



1910, 162; Geitler, Die Siisswasserflora 

 Deutschlands, Osterreichs und der Schweiz, 

 Jena, 12, 1925, 457.) 



