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1032
COMPREHENSIVE KEY
Cells spherical to cylindrical. Develop in small clusters, the compact clusters of 4 to 20 cells being widely separated in an almost spherical and seemingly cartilagenous capsule, the outer laj^er of which is neither sharply differentiated nor obviously deliquescent. As each cluster proliferates, it eventually separates into a number of smaller clusters within the zoogloea. Single cells are rare. At some stage individual clusters leave the mass as a result of either swelling and dispersion of the whole mass or a softening of the mass at one or more points. After separation, the cluster becomes motile. The process of separation of clusters occupies 3 weeks. Generation time is approximately two days.
Thiocystis p. 42
Cells spherical to cylindrical; heavily encapsulated, the capsules remaining attached to form zoogloeae. The individual capsules are very thick. Following division the cells become separated in space by the developing capsules and are eventually arranged at an obtuse angle to each other. Swarming is preceded by a softening of the capsule and an irregular rearrangement of the cells. Individual cells separate by a slow rotatory action and once free are actively motile (c/. Chromatium) . Cells are pale gray. Sulfur granules are small and confined to the peripheral layer of cytoplasm
Thiothece p. 42
7. Cells spindle-shaped; 1.5 to 1.7 by 2.5 to 5.0 microns. Cell families may consist of a long irregular body made up of cells 2 to 3 layers thick arranged in parallel fashion. When separated from other cell masses the cells rearrange to form an open pyramidal network in which the cells meet only at their tips. Colonies may be several hundred microns across and resemble Hydrodictyon of the blue -green algae. Small cell groups detached from the mass are motile; compact masses form under unfavorable conditions. Individual cells contain an elongated vacuole and are pale in color; sulfur is confined to the peripheral cytoplasm
Thiodictyon p. 41
Cells compressed into a compact mass; colored rose-red; surrounded by a capsule composed of an inner, poorly refracting layer and an outer, strongly refracting layer. Placed in a favorable environment, the cyst cracks and the cell mass slowly creeps out (1 to 2 days). The empty cyst remains unchanged for some time. The group of cells does not disperse but grows in an irregularly contoured mass. Whole families are motile. Most cells are spherical. Division occurs only in one direction. Cells may be compressed or may be freelj^ separated in the non-encysted state. There are rarely more than two to four within a group in the colony. They are continually changing position and proximity in the colony. Internal colonial movement can occur without much lateral movement. Coordinated lateral movement is amoeboid. Single cells occasionally become isolated from the mass and then are drawn back. Masses ultimately may separate into smaller groups. No capsular material can be discerned in the families. Families can be penetrated by small motile bacteria with ease. Winogradsky considered that the connection was via plasma threads, but he was unable to demonstrate them. He considered the dense compact masses to occur in the presence of O2 and the open structure in the presence of hydrogen sulfide
Amoebobacter p. 44
Shapeless, thick aggregates of small spherical vividly colored cells; non-motile; do not form hollow spherical structures. The extremely smooth surface of the colony suggests a limiting capsular material, but no obvious capsule is visible. Eventually growth, in the form of threads and flaps, appears on the surface, and cells become separated
Thiopolycoccus p. 45
