i82 SULPHUR BACTERIA 



Beggiatoa alba. Also, if Warming's drawings are correct, the 

 threads divide by simple fission, a process in which the forma- 

 tion of transverse walls plays no part. 



Hinze (i — 2) examined an organism under this name which 

 evidently tallies with the Beggiatoa mirabilis of Cohn, but not 

 with that of Warming. The membrane is double contoured, 

 and is not composed of cellulose. The transverse walls are 

 thinner than the outside walls and stain with ruthenium red, 

 safranin, and other reagents that stain pectin bodies. Inside 

 the wall is a peripheral layer of plasma (Rindenschicht) in 

 which are numerous fine red granules which stain with hasma- 

 toxylin and alleged by Hinze to be chromatin. Inside this is 

 a large vacuole occupying the chief space of the cell and 

 containing a large number of solid granules which often show 

 molecular movements. The plasma is granular, homogeneous, 

 and contains numerous sulphur granules. 



Chromatium Okenii. 



The observations on the intimate structure of this well- 

 known and much-studied organism are few and unsatisfactory. 



Dangeard states that a colourless membrane encloses an 

 alveolar cytoplasm, and that the colour is diffused throughout 

 the cytoplasm. He made out a " Centralkorper " which 

 corresponded to the Centralkorper of the Cyanophycece, and 

 regarded this as the nucleus of the cell. Attempts to dis- 

 tinguish in bacterial cells in general between a peripheral and 

 a central body (Rindenschicht and Centralkorper) date from 

 Biitschli's investigations, and his conclusions are nowadays 

 not accepted. If we may judge from the structure of the 

 allied species Chromatium Linshaueri it seems as though 

 Dangeard's conclusions were influenced more by Biitschli's 

 conception of the cell than from the evidence of structure 

 presented by the cell itself. 



AcHKOMATiUM OXALIFERUM (Schewiakoff). 



Under the various names of Achromatiimi oxaliferum 

 (Schewiakoff), M odder ula Hartiengi (Frenzel), and Hillhousia 

 mirabilis (West and Grifiiths), the intimate structure of the 



