1. Chlorochromatium aggregatum Lauterborn, 1906. (AUgem. botan. Ztschr., 19, 1906, 196.)
ag.gre.ga′tum. L. part. adj. aggregatus flocked together, clumped.
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 attached in a chain.
Anaerobic.
Habitat: Mud and stagnant water containing 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 colony, as Geitler proposed (Die Süsswasserflora Deutschlands, Österreichs und der Schweiz, Jena, 12, 1925, 460). The reported and personally observed sizes of such units show that the extreme limits are linked by a complete series of transitions.
Illustrations: Buder, Ber. deut. botan. Ges., 31, 1914, Generalversam., Pl. XXIV, fig. 1-5; Perfiliev, Jour. Microbiol. (Russian), 1, 1914, fig. 1-5, p. 213.
Genus VI. Cylindrogloea Perfiliev, 1914-
(Jour. Microbiol. (Russian), 1, 1914, 223.)
Cy.lin.dro.gloe′a. Gr. noun cylindrus cylinder; Gr. noun gloea gum; M.L. fem. n. Cylindrogloea cylindrical gum.
Sulfur green bacteria consisting of small ovoid to rod-shaped cells growing in association with a filamentous, colorless, central bacterium, thus forming colonies of a cylindrical shape. Non-motile. The green component contains a chlorophyllous pigment different from the common chlorophylls of green plants and from bacteriochlorophyll. Capable of photosynthesis in the presence of hydrogen sulfide without depositing sulfur globules in the cells.
The type species is Cylindrogloea bacterifera Perfiliev.
1. Cylindrogloea bacterifera Perfiliev, 1914. (Jour. Microbiol. (Russian), 1, 1914, 223.)
bac.te.ri′fe.ra. Gr. neut. n. bactrum a rod; M.L. mas. n. bacter rod (a combining form); L. verbal suf. fer bearing; M.L. adj. bacterifera rod-bearing.
Individual green components ovoid to rod-shaped, about 0.5 to 1 by 2 to 4 microns, very similar to those of the complex Chlorobacterium symbioticum and Chlorochromatium aggregatum with which they may well be identical. The central filamentous bacterium is embedded in a slime capsule of considerable dimensions. This, in turn, is surrounded by a layer of green bacteria, usually one cell thick. The green organisms may form a very dense outer covering, or they may be more sparsely distributed over the slime capsule. The entire unit is again surrounded by a sizeable slime zone. Aggregates measure about 7 to 8 microns in width and up to 50 microns in length; they are non-motile. Both components appear to be non-spore-forming.
Habitat: Mud and stagnant water containing rather high concentrations of hydrogen sulfide and exposed to light.
Illustration: Perfiliev, ibid., fig. 6-11, p. 213.
Perfiliev rightly emphasizes, as Buder had done for Chloronium mirabile, the provisional nature of thus using a generic designation for an apparently stable complex composed of two different organisms. It remains possible that the last three genera of symbiotic entities represent fortuitous combinations whose occurrence is conditioned by environmental factors. If so, the generic terminology would be devoid of any taxonomic significance, and the green bacteria should be relegated to more appropriate genera. Indications suggestive of this state of affairs can be found in the literature; for example in Utermöhl's observation (Archiv
