FAMILY I. THIORHODACEAE 



45 



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



2. Amoebobacter bacillosus. 

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



3. Amoebobacter granula. 



1. Anioebobacler 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 occupy- 

 ing the peripherj^ as a shallow layer. These 

 are reminiscent of stages in the development 

 of Lamprocystis. 



Habitat: Mud and stagnant water con- 

 taining hj^drogen sulfide and exposed to 

 light; sulfur springs. 



Illustrations: Winogradsky, loc. cit., PI. 

 Ill, fig. 1-6. 



2. Amoebobacter bacillosus Winograd- 

 sky, 1888. (Winogradsky, Schwefelbac- 

 terien, 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 pseudo- 

 vacuoles (aerosomes). Sulfur globules de- 

 posited exclusively in peripheral proto- 

 plasmic layer, usuallj' quite small. 



Mij'oshi's incomplete description of Thio- 

 derma roseum (loc. cit.), type species of 

 genus Thioderma, is sufficient to make prac- 



tically certain that it is identical with 

 Amoebobacter bacillosus. The description of 

 Thiodictyon elegans Winogradsky {op. cit., 

 1888, 80) suggests that it cannot be distin- 

 guished from this species. 



Habitat: Mud and stagnant water con- 

 taining hydrogen sulfide and exposed to 

 light; sulfur springs. 



Illustrations: Zopf, Z. Morphol. d. 

 Spaltpfl., Leipzig, 1882, PI. V, fig. 26-27; 

 Winogradsky, op. cit., 1888, PI. Ill, fig. 7. 



3. Amoebobacter granula Winograd- 

 sky, 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 be- 

 comes difficult if not impossible to make 

 accurate observations of the cell shape. 



Habitat: Mud and stagnant water con- 

 taining hj-drogen sulfide and exposed to 

 light; sulfur springs. 



Illustration: Winogradsky, loc. cit., PI. 

 Ill, fig. 8. 



Genus IX. Thiopolycoccus Winogradsky, 1888. 



(Schwefelbacterien, Leipzig, 1888, 79.) 



Thi.o.po.ly.coc'cus. Or. noun thium sulfur; Gr. adj. poly many; Gr. noun coccus a berry; 

 M.L. noun coccus; M.L. mas.n. Thiopolycoccus with man}'- sulfur cocci. 



Sulfur purple bacteria which form dense aggregates of rather solid construction and ir- 

 regular 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, mo- 

 tility not observed. Contain bacteriochlorophyll and carotenoid pigments, so that the 

 aggregates, in accord with the dense packing with individual cells, appear distinctly red. 



