122 SULPHUR BACTERIA 



to Bersa, are composed of calcium carbonate. There is a 

 single large polar cilium, which is plainly visible without special 

 preparation, and which is as long as, or even longer, than 

 the cell. Cell-division takes place by simple fission following 

 upon a slight elongation of the cell, which during the process 

 does not come to rest. The stages in division are the same 

 as in Achromatium oxaliferum. After fission has taken place 

 the two daughter cells are connected for a period by a trans- 

 verse band of liyalinc material. The cells gradually draw 

 apart, and complete separation is efl'ected. The number of 

 sm.all globules of sulphur is increased when sulphuretted hydro- 

 gen is added to the medium. 



Habitat. — Found in foul mud samples from the University 

 garden in Graz (Austria). 



Genus 2. — Thiophysa (Hinze). 



Literature. — Hinze (3), 1903 ; Nadson (5), 1914. 



A genus of two species. The cells are globular or ovoid, 

 colourless, and motile. The movement, which is slow, is one 

 of translation and of rotation. Cilia have not been found. 

 The cells contain a peripherally placed plasma, and a large 

 central vacuole. Division takes place l)y fission, following 

 a slight preparatory elongation. Both uni- and diplo-cocci 

 are conmion. 



Thiophysa volutans (Hinze). 



Literature. — Hinze (3), 1903 ; Nadson (5), 1914 ; Kolkwitz 

 (10). 1918. 



Description. — This species was found in a sulphur spring 

 in the Gulf of Naples, near Castellamare. The floor containing 

 the organism was made up of fine calcareous sand, and smelt 

 strongly of H2S. The calcium does not appear to penetrate 

 the cell membrane. Diameter of cells, 7 — i8/a; maximum = 

 28-9)U, long, and i7-9/i, broad (Fig. 17). 



It has also been found in the brine ditches at Artern 

 (Saxony), and at the sea-bottom near Hapsalu in Esthonia. 



