THE LEUCO-THIOBACTERIA 



123 



Thiophysa macrophysa (Nadson). 



Literature. — Nadson (5) 1914. 



Description. — This species is distinguished from the 

 preceding by its larger average size. The diameter of cell is 

 21 — 40jU.. It is, therefore, a much larger organism than the 

 preceding, and, in addition, there is a physiological distinction, 

 for whilst the Th. voliitans is confined to marine waters, this 

 species flourishes only in a medium containing much less 

 sodium chloride, namely \ per cent. 



b c 



Fig. 17. — Thiophysa voliitans. 



X 500. 



Genus 3. — Thiosph^rella (Nadson). 

 Literature. — Nadson (5), 1914 ; Bavendamm, 1924. 

 One species, Thiospha;rella amylifera. The following de- 

 scription is translated from Bavendamm's work, as Nadson's 

 work was not available. Cells round, often ellipsoidal, 6^ long, 

 and 4-8)U, broad. The membrane is relatively thick, dense, 

 and highly refractive, and surrounding it is a colourless 

 slime layer. The protoplasm is normally not quite colour- 

 less, but has a steel-grey tint. In the plasma are sulphur 

 globules of various sizes, and, in addition, a substance of a 

 starchy nature, which colours a dark red or violet when treated 

 with iodine. The cells possess a slow movement, similar to 

 that of Achromatium. Reproduction is by fission (Fig. 17 

 a and b). 



Genus 4. — Thiovulum (Hinze). 

 Literature. — Warming, 1876 ; Migula (3), 1900 ; Molisch 

 (5), 1912 ; Hinze (6), Lautcrborn (7), 191 5 ; Baven- 

 damm, 1924. 



