RHODO-THIOBACTERIA 171 



Habitat. — In sulphur springs, and other waters containing 

 sulphuretted hydrogen in solution. 



Thiothece and Thiopolycoccus. 



The genus Thiothece was founded by Winogradsky (2) to 

 include a single organism, which he named Thiothece gelatinosa 

 (Fig. 47). The cells of this organism are 

 small and either globular or ellipsoidal- 

 cylindrical. They measure 4*2^ in diameter, 

 and it is stated without experimental 

 evidence that they divide only in one 

 plane. For this reason the genus is placed 

 in the Amoshohacteriacece. 



Winogradsky observed the emergence „ ^"^^^1 ■ ^ 

 of the cells from the slime, and their gelatinosa. x 1000. 

 subsequent transition into the swarm con- 

 dition. Each cell has a single cilium. The colour of the cells 

 is an intensely grey violet, or pale rose, or even yellowish or 

 dirty green. The sulphur globules are located in the peripheral 

 layer. Winogradsky also noted the similarity of the organism 

 to one of the pleomorphic forms of Bacterium ritbescens, but 

 rejected the idea that the two were identical. Beggiatoa 

 roseo-persicina also exhibits a pleomorphic phase that appears 

 to be identical with the organism described by this investigator. 

 The figure which he gives of Thiothece is one which it would not 

 be difficult to match in the drawings of several of the better- 

 known bacteria. In addition, the name was given from 

 observation of only the adult condition of the organism, and 

 its life-history was not investigated. 



The same objections apply to the genus Thiopolycoccus 

 of the same writer. This was stated to differ from Thiothece 

 only in the absence of cilia after release from the slime. The 

 differences between the two organisms which have given rise 

 to these two genera are not sufficiently marked to warrant 

 one being regarded as a variant of the other, far less suffi- 

 ciently marked to necessitate founding two genera. It is 

 considered that the objections just stated are such as to 



