1 84 SULPHUR BACTERIA 



workers the protoplast of Achromatium oxaliferum is shown as 

 two well-marked regions, an outer which was considered as the 

 Rindenschicht (peripheral layer), and an inner region which was 

 regarded as the Centralkorper (central body). Later workers 

 consider that this distinction does not exist, and that the earlier 

 workers made the same error as we have noted above in the 

 investigations of Chromatium Okenii. 



In the organism examined by West and Griffiths, by 

 Virieux, and by the author, the protoplasm showed no such 

 distinction (Fig. 51). The meshes are occupied each by a large 

 globule, varying from 6)u- to lOju, in diameter, of a calcium salt. 

 These are steel blue in colour, and highly refringent. Outside 

 the cell they crystallize as fiat rhombohedra or rhombic prisms. 

 West and Griffiths consider the salt to be calcium carbonate, 

 but Virieux states that when treated with hydrochloric acid, 

 it disappears without effervescence, and so considers it to be 

 calcium oxalate. 



Virieiix's Investigation of Achromatium Oxaliferum. — This 

 writer gives the name of granules to the calcium globules 

 which fill the alveoles, and states that when they are 

 dissolved, refringent particles which are neither chromatin 

 nor metachromatic granules appear in the plasma. The 

 metachromatic granules are soluble in dilute acetic acid, 

 whereas the refringent particles are insoluble in that fluid. 

 These particles are further distinguished by turning red when 

 the cell is treated with haemalum, the rest of the cell being 

 violet. He gives the name corpuscles to the refringent particles 

 and considers that they are composed of sulphur, in spite of 

 the fact that his microchemical reactions for sulphur did not 

 give positive results. He bases his conclusion on the fact that 

 they increase in number when the organism is supplied with 

 sulphuretted hydrogen. They vary from 0-5ju, to 2/a in diameter 



(Fig. 5I&). 



In addition, Virieux maintains that grains of chromatin 

 are present which are so small that they are not visible unless 

 the magnification is greater than lOOO diameters. The sum 

 total of these particles is, according to him, the nucleus. 



