FAMILY THIOKHODACEAE 



845 



the cells. This genus is so much like Thiothece that it is doubtful whether a distinc- 

 tion can be maintained. 



The type species is Thiocapsa roseopersicina Winogradsky. 



Key to the species of genus Thiocapsa. 



I. Individual cells about 3 microns in diameter. 



1. Thiocapsa roseopersicina. 

 II. Individual cells about 1.5 microns in diameter. 



2. Thiocapsa floridana. 



1. Thiocapsa roseopersicina Winograd- 

 sky. (Schwefelbacterien, Leipzig, 1888. 

 84.) From Latin roseus, rose-colored 

 and persicum, peach; M.L., peach- 

 colored. 



Cells: Spherical, 2.5 to 3 microns in 

 diameter, occurring in families of irregu- 

 larly arranged individuals held together 

 in a common slime capsule. Motility 

 not observed, t^sually a distinct rose- 

 red. Stored sulfur droplets may attain 

 a considerable size. 



Habitat: Mud and stagnant bodies of 

 water containing hydrogen sulfide and 

 exposed to light; sulfur springs. 



Illustration: Winogradsky, loc. cit., 

 Plate IV. fig. 15. 



2. Thiocapsa floridana Uphof. (Uphof , 



Arch. f. Hydrobiol., 18, 1927, 84; Thio- 

 capsa minima Issatchenko, Borodin Ju- 

 bilee Volume, p. 6, 1929?.) From the 

 locality, Florida, w^here the organism 

 was first found. 



Cells: Spherical. About 1.5 microns 

 in diameter. In groups of irregular 

 colonies, each surrounded by a common 

 capsule, several colonies being stuck 

 together. Motility not observed. 



Source: Palm Springs, Florida and 

 Lake Sakskoje, near Eupatoria, Crimea. 



Habitat : Mud and stagnant water con- 

 taining hydrogen sulfide and exposed to 

 light; sulfur springs. Probably ubiqui- 

 tous. 



Illustration: Uphof, loc. cit., 83, 

 fig. VI. 



Genus IV. Thiodictyon Winogradsky . 



(Winogradsky, Schwefelbacterien, Leipzig, 1888, 80; Rhododictyon Orla-Jensen, 

 Cent. f. Bakt., II Abt., 22, 1909, 334.) From Greek theion, sulfur and dictyon, net. 



Cells rod-shaped, frequently with pointed ends, somewhat resembling spindles. 

 Form aggregates in which the cells become arranged end to end in a net-like struc- 

 ture, somewhat reminiscent of the shape of the green alga Hydrodictyon. The shape 

 is not constant; cells may also form more compact masses. Sometimes groups of 

 cells separate from the main aggregate by active movements. Common gelatinous 

 capsule not observed. Contain bacteriochlorophyll and carotenoid pigments; cells 

 usually very faintly colored. Capable of photosynthesis in the presence of hydrogen 

 sulfide; the cells then store sulfur as small globules. 



The type species is Thiodictyon elegans Winogradsky. 



1. Thiodictyon elegans Winogradsky. 

 (Winogradsky, Schwefelbacterien, Leip- 

 zig, 1888, 80; Thiodictyon minus Issat- 

 chenko, Recherches sur les microbes de 

 I'ocean glacial arctique, Petrograd, 1914, 

 251.) From Latin elegans, tasteful, 

 elegant. 



Rods: 1.5 to 1.7 bv 2.5 to 5 microns; or 



longer just prior to cell division. Usu- 

 ally contain a large pseudovacuole 

 (aerosome), leaving a rather thin proto- 

 plasmic sheath along the cell wall. 



Sulfur droplets: Generally quite small, 

 and deposited exclusively in the thin 

 protoplasmic layer. 



