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SECTION J
1. Cells occur singly; motile by means of polar flagella; may be encapsulated and may form zoogloeae but if so, do not oxidize hydrogen sulfide and do not deposit sulfur internally
2
Cells occur singly, in pairs or in short chains; non-motile; individual cells encapsulated and usually contain two pseudovacuoles per cell which makes them buoyant and which may give them a polygonal appearance; sulfur is deposited internally
Rhodothece p. 50
Cells occur in well-defined aggregates. When growing in the presence of hydrogen sulfide, sulfur is deposited internally
4
2. Hydrogen sulfide is not oxidized. Sulfur is not deposited internally
Rhodopseudomonas p. 53
Hydrogen sulfide is oxidized, and globular sulfur is deposited internally
3
3. Cells of uneven width and length; often swollen, spindle-shaped and filamentous
Rhabdomonas p. 48
Cells of uniform width; spherical to cylindrical, the latter sometimes slightly curved
Chromatium p. 50
Note: Single cells of Thiothece, Thiocystis and Lamprocystis resemble Chromatium very closely. Also cells of Thiospirillum violaceum are indistinguishable from curved cylindrical forms of Chromatium.
4. Cells occur in cubical packets
Thiosarcina p. 39
Cells in young colonies appear as flat sheets in which cells are arranged in parallel rows embedded in a capsular material. In an unfavorable position or environment, irregular clumping of cells may occur
Thiopedia p. 40
Other than above
5
5. Individual cells or cell masses embedded in conspicuous capsules or zoogloea
6
Individual cells or cell masses apparently devoid of capsular material although cells within the mass may be clearly separated in space
7
6. Cells spherical, occurring in large numbers well separated in a conspicuous common slime capsule. In dry conditions the capsular material forms a double contoured membrane around the cells. On moistening, the mass slowly swells and bursts. As the liberated cells divide they form a fiat, spreading colony in which the cells are no more than three layers deep but are separated from each other by capsular material
Thiocapsa p. 41
Cells spherical and encapsulated. In the early stages of growth of the colony, cells form
in tetrads[1] resembling those of Thiocystis. Further division of the cells gives rise to a compact opaque mass of cocci embedded in a large slime capsule. This is followed by formation of arched fragments similar in appearance to sections of a hollow sphere, the fragments being arranged as if on the surface of a sphere within the capsule. Continued growth of the arched fragments results in their edges touching but not coalescing. Infolding of the arched pieces takes place, finally almost filling the internal cavity and producing a network resembling a sponge. The enveloping capsule eventually ruptures, liberating fragments of the zoogloeal network which reorganize into small groups interlinked by single cocci. Under unfavorable conditions the cocci are vacuolated, and sulfur is confined to the peripheral cytoplasm. Free cells are motile (cf. Chromatium) . The total transformation occurs in 40 days
Lamprocystis p. 43
1031
- ↑ Winogradsky considered that cells which form tetrads divide in three directions, the result being a four-pointed group rather than a fiat group of four.
