FAMILY CHLOROBACTERIACEAE 



873 



1. Chlorobacterium symbioticum Lau- 

 terborn. (Lauterborn, Verhandl. na- 

 turhist.-medizin. Vereins, Heidelberg, 

 N.F., 13, 1915, 429; Chroostipes linearis 

 Pascher, Die Siisswasserflora Deutsch- 

 lands, Osterreichs und der Schweiz, 

 Jena, 13, 1925, 116.) From Greek, living 

 symbiotically. 



Cells: Rod-shaped, about 0.5 by 2 to 5 

 microns, often slightly curved. Xon- 

 motile. 



Occur as a peripheral covering of cer- 

 tain protozoa with which they may form 

 a symbiotic unit. 



It is iKjt certain that this is a green 

 sulfur bacteriimi; the description of 

 localities where it was found fail to 

 mention the presence of hydrogen sul- 

 fide in the environment which should be 

 a prcM-equisite for a member of this 

 group. 



Source: Reported from a number of 

 ])ools in Germany. 



Habitat: Stagnant water. 



Illustrations: Lauterborn, loc. oil., 

 PI. Ill, fig. 34-36; Pascher, loc. cit., 

 fig. 149. 



Genus V. Chlorochromatiiun Laiderburn. 



(Lauterborn, Allgem. botan. Ztschr., 19, 1906, 196; Chloronium Buder, Ber. d. 

 deut. bot. Ges., 31, 1914, General versammlungsheft, 80.) From Greek chloros, green 

 and chroma, color. 



Green sulfur bacteria, ovoid to rod-shaped with rounded ends, occurring as barrel- 

 shaped aggregates, consisting of a rather large colorless bacterium with a polar flagel- 

 lum as the center, surrounded by the green bacteria, arranged in 4 to 6 rows, ordi- 

 narily from 2 to 4 cells high. The entire conglomerate behaves like a unit, is motile, 

 and multiplies by the more or less simultaneous fission of its components. 



The green constituents contain a chlorophyllous pigment which is not identical 

 with the common green plant chlorophylls or with bacteriochlorophyll. Capable 

 of photosynthesis in the presence of hydrogen sulfide, but do not store sulfur globules 

 in the cells. 



The type species is Chlorochromaiium aggrcgatum Lauterborn. 



1. Chlorochromatium aggregatum Lau- 

 terborn. (Lauterborn, Allgem. botan. 

 Ztschr., 19, 1906, 196; Chloronium mira- 

 bile Buder, Ber. deut. botan. Ges., 31, 

 1914, Generalversammlungshef t , SO.) 

 From Latin aggregatus, grouped. 



Cells of the green component 0.5 to 

 1.0 by 1.0 to 2.5 microns, mostly from 8 

 to 16 individuals surrounding the central 

 bacterium. Size of the total barrel- 

 shaped unit variable, generally 2.5 to 5 

 by 7 to 12 microns. Occasionally a group 

 of the complex colonies may remain at- 

 tached in a chain. 



Anaerobic. 



Habitat: Mud and stagnant water con- 



taining rather high concentrations of 

 hydrogen sulfide and exposed to light. 



There is at present no good reason for 

 distinguishing 2 varieties (forma typica 

 and forma minor) or even species, on the 

 basis of size differences of the colonj-, 

 as Geitler proposed (Die Siisswasser- 

 flora Deutschlands, Osterreichs und der 

 Schweiz, Jena, 12, 1925, 460). The re- 

 portetl and personally observed sizes of 

 such units show that the extreme limits 

 are linked by a complete series of transi- 

 tions. 



Illustrations: Buder, loc. cit., PI. 

 XXIV, fig. 1-5; Perfiliev, Jour. Micro- 

 biol. (Russian), 1. 1914, 213, fig. 1-5. 



(Jour. Microbiol. 

 Greek gloios, a glutinous substance. 



Genus VI. Cylindrogloea Perfiliev. 

 (Russian), /, 1914, 223.) From Latin cylindrus, cylinder and 



