RHODO-THIOBACTERIA 149 



regarded its capacity for storing lime as an outstanding feature, 

 and considered it to be the first of a new class of bacteria, which 

 he named lime bacteria, because the globules are composed 

 of calcium carbonate. It must at present remain doubtful 

 whether lime takes an active part in the metabolism of this 

 organism, for its appearance seemed to be only occasional, 

 and to accompany the formation of the stainable globules 

 which arc evidently reserve material. It is possible that it 

 may be a waste product in the process which results in the 

 formation of the nitrogenous reserve material (the stainable 

 globules). The matter must await further investigation. The 

 cell contents vary somewhat, the cell being sometimes full of 

 sulphur granules, and at other times of lime granules and the 

 stainable corpuscles already mentioned. Nothing is at present 

 known of the conditions determining these differences, but 

 they are probably due to environmental changes. (Compare 

 Fig. 30A and Fig. 31.) 



Chromatium violascens (Perty). 



Literature. — Perty, 1852. 



The violet colour is the distinctive feature of this organism. 

 It was found on the wall of a glass vessel containing decompos- 

 ing Chara. The cells are described as spherical or ellipsoidal, 

 2 — 3jL(- long, and very variable in size and shape. 



Chromatium cuculliferum (Gicklhorn). 



Description. — The cell is globular or slightly ovoid, and 

 measures 6 X 4jm. According to Gicklhorn its very small size 

 distinguishes the species from others of the same genus. It 

 possesses a single cilium, and rotates very slowly about its 

 longitudinal axis. 



Description. — The sulphur globules are congregated at one 

 end, whilst the cilium is invariably attached to the other end 

 (Fig. 32). 



The cells are colourless, and the size constant. 



Habitat. — -In water containing decomposing Algee, taken 

 from Botanic Gardens, Graz. 



The absence of colour is a feature which makes ques- 

 tionable its inclusion in the genus Chromatium. Baven- 

 damm, however, identifies it with Chromatium Warmiiwii 



