512 GENERAL SYSTEMATIC BACTERIOLOGY 



Families enclosed in a thick gelatinous cyst. Cells capable of swarming and 

 very loosely embedded in a common gelatin. When the swarm stage supervenes, 

 the cells lie more loosely, the gelatin is swollen, and the cells swarm out singly and 

 rather irregularly. 



Orla-Jensen (1909, p. 334) renamed this genus Rhodothece. 

 Buchanan (1918, p. 469) included this as the third genus of the 

 tribe Amoehohaderieae with the description: 



Cells spherical, in families enclosed in a thick, gelatinous cyst. Cells capable 

 of swarming and very loosely embedded in a common gelatin. When the swarm 

 stage supervenes, the cells lie more loosely, the gelatin is swollen, and the cells 

 swarm out singly and rather irregularly. 



The type species is Thiothece gelatinosa Winogradsky. 



Bergey et al. (1923, p. 399) followed Buchanan. 

 Thiothrix. A genus of sulphur bacteria proposed by Winogradsky 

 (1888, p. 39) with the following diagnosis: 



Faden unbeweglich, gegliedert, mit einer zarten Scheide, einen deutlichen 

 Gegensatz von Basis und Spitze zeigend, durch ein Gallertpolster an feste Gegen- 

 stande befestigt, unter normalen Wachsthumsbedingimgen dicht mit Schwefel- 

 kornern gefiillt; Reproduction durch Stabchengonidien, welche auf festen Gegen- 

 standen kriechend sich langsam bewegen, nach kurzer Bewegungsdauer sich auf 

 verschiedene Gegenstande festsetzen und zu Faden auswachsen. 



The genus is recognized by many subsequent authors, among them 

 Migula (1897, p. 40), Fischer (1897, p. 32), Migula (1894, p. 238) says: 

 ^'Thiothrix Winogradsky. Unverzweigte in feine Scheiden einge- 

 schlossene, unbewegliche Faden mit Teilung der Zellen nach einer 

 Richtung des Raumes. Die Zellen enthalten Schwefelkornchen)," 

 Chester (1899, p. 64), Migula (1900, p. 1039), Chester (1901, p. 378), 

 Fischer (1903, p. 61), E. F. Smith (1905, p. 162), Orla-Jensen (1909), 

 Heim (1911, p. 254), Frost (1911, p. 60). The generic description by 

 Smith is as follows: 



Threads attached, not uniformly thick, enveloped in a delicate sheath which is 

 not easily demonstrable, non-motile, contents containing sulphur granules. The 

 threads produce rod-shaped conidia at their end. These conidia, which are self- 

 motile by means of a slow, creeping motion, attach themselves by one end to any 

 sort of substratum, extrude a slime cushion at the base, bend over ordinarily in 

 their middle to a nearly right angle and grow into a new thread. Habitat, hot 

 sulphur springs. 



Buchanan (1918, p. 463) included this genus as the first in the family 

 Beggiatoaceae with the following description: 



