132 SULPHUR BACTERIA 



composition of the slime seems to indicate the first step in the 

 evolution of the group towards a miore complicated organization. 

 Habitat. — Marine. 



Thiobacillus thiogenus (Molisch), Ellis. 

 Syn. Bacillus thiogenus (Molisch). 



A marine bacillus. It is described as being 0"9 — i-3/x 

 thick and 2-6/x long. 



Habitat. — Marine. 



Description. — The two organisms Bacterium crystalliferimi 

 (Gicklhorn) and Bacterium reliformans (Gicklhorn) do not store 

 sulphur ill the cells but deposit it outside. Accordingly they 

 cannot be included in the sulphur bacteria. Bavendamm 

 suggests that their place is probably in the group of thionic 

 acid bacteria. 



Genus 2. — Thiopseudomonas (Ellis). 



Description.- — Colourless, rod-shaped, motile or non-motile 

 cells. Cilia polar. 



The introduction of this genus is necessary although so 

 far no definite species can be assigned to it. The two terms 

 Thiobacillus and Thiopseudomonas must necessarily go together, 

 for in most cases all motile rod-shaped forms are assigned to 

 the genus Bacillus, before it is known whether the cilia are 

 peritrich or polar. In most cases the difficulty of staining 

 the cilia accounts for the want of knowledge as to the dis- 

 position of the cilia. 



The two organisms Pseudomonas bipnnctatiis (Gicklhorn) 

 and Pseudomonas hyalina (Gicklhorn) have been erroneously 

 jjlaced in the genus Pseudomonas by their discoverer. In 

 their general character they have no resemblance to the 

 organisms placed in this genus. They are described here 

 because they have been labelled as sulphur bacteria on the 

 strength of their habitat, namely, water containing hydrogen 

 sulphide in solution. Also, they do not store sulphur in their 

 cells. 



Pseudomonas bipuncta tus. Colourless transparent cylin- 

 drical cells, 8 — I2/X long and 3 — 5/a broad. The single polar 



