Page:Bergey's manual of determinative bacteriology.djvu/67

 II. Cells distinctly rod-shaped, about 1.5 to 2 microns in width by 2 to 4 microns in length.

III. Cells spherical, quite small, about 0.5 to 1 micron in diameter.

1. Amoebobacter roseus Winogradsky, 1888. (Schwefelbacterien, Leipzig, 1888, 77.)

ro′se.us. L. adj. roseus rosy.

Cells spherical to ovoid, 2.5 to 3.5 microns in width and up to 6 microns in length. Motile. Often contain pseudovacuoles. Cell aggregates often form transitory hollow spheres or sacks with the bacteria occupying the periphery as a shallow layer. These are reminiscent of stages in the development of Lamprocystis. Habitat: Mud and stagnant water containing hydrogen sulfide and exposed to light; sulfur springs.

Illustrations: Winogradsky, ''loc. cit.'', Pl. III, fig. 1-6.

2. Amoebobacter bacillosus Winogradsky, 1888. (Winogradsky, Schwefelbacterien, Leipzig, 1888, 78; Thioderma roseum Miyoshi, Jour. Coll. Sci., Imp. Univ. Tokyo, Japan, 10, 1897, 158.)

ba.cil.lo′sus. L. dim. noun bacillus a small staff or rod; M.L. adj. bacillosus full of (made up of) small rods.

Cells rod-shaped, about 1.5 to 2 microns by 2 to 4 microns. Cells contain pseudovacuoles (aerosomes). Sulfur globules deposited exclusively in peripheral protoplasmic layer, usually quite small.

Miyoshi's incomplete description of Thioderma roseum (loc. cit.), type species of genus Thioderma, is sufficient to make practically certain that it is identical with Amoebobacter bacillosus. The description of Thiodictyon elegans Winogradsky (op. cit., 1888, 80) suggests that it cannot be distinguished from this species.

Habitat: Mud and stagnant water containing hydrogen sulfide and exposed to light; sulfur springs.

Illustrations: Zopf, Z. Morphol. d. Spaltpfl., Leipzig, 1882, Pl. V, fig. 26-27; Winogradsky, op. cit., 1888, Pl. III, fig. 7.

3. Amoebobacter granula Winogradsky, 1888. (Schwefelbacterien, Leipzig, 1888, 78.)

gra′nu.la. L. dim. noun granulum a small grain; M.L. fem. n. granula a small grain. Cells spherical, small, about 0.5 to 1.0 micron in diameter. Faint pigmentation; the sulfur inclusions give the cell masses a black appearance. Aggregates are apt to consist of closely-knit masses which are difficult to separate.

When sulfur is stored, a single droplet usually fills most of the cell. Because of the high refractive index of this globule, it becomes difficult if not impossible to make accurate observations of the cell shape.

Habitat: Mud and stagnant water containing hydrogen sulfide and exposed to light; sulfur springs. Illustration: Winogradsky, ''loc. cit.'', Pl. III, fig. 8.

Thi.o.po.ly.coc′cus. Gr. noun thium sulfur; Gr. adj. poly many; Gr. noun coccus a berry; M.L. noun coccus; M.L. mas. n. Thiopolycoccus with many sulfur cocci.

Sulfur purple bacteria which form dense aggregates of rather solid construction and irregular shape. The colonies appear, in contrast with those of Amoebobacter, non-motile and do not tend to form hollow zoogloeal structures by which they are differentiated from Lamprocystis. Cell masses held together by mucus which does not, however, appear as a regular capsule. Large clumps may fissure with the formation of irregular shreds and lobes which continue to break up into smaller groups of cells. Individual bacteria spherical, motility not observed. Contain bacteriochlorophyll and carotenoid pigments, so that the aggregates, in accord with the dense packing with individual cells, appear distinctly red.