MICROCHEMISTR Y. 



47 



3. Sulphur, S. 



68. The sulphur which occurs in various Bacteria in the 

 form of strongly refractive spheres (cf. Fig. 1 8, I, a-c) is, 

 according to Cohn (I, 178), insoluble in water and hydro- 

 chloric acid, but soluble in an excess of absolute alcohol, in 

 hot potash, or in sodium sulphite. Nitric acid and potassium 

 chlorate dissolve them at ordinary temperatures, as does car- 

 bon bisulphide ; but the entrance of the latter into the cells 

 of the Bacteria must be aided by previously killing them 

 with sulphuric acid or by drying. According to Wino- 

 gradsky (I, 521), this solubility in carbon bisulphide is not 

 complete, although the insoluble residue in this reagent is 

 always small. According to Butschli (I, 6), the granules of 

 sulphur are soluble in twenty-four hours in artificial gastric 

 juice, or in a 10$ soda solution. 



69. Various observations of Winogradsky (I, 518) ex- 

 plain the accumulation of the sulphur granules. Accord- 

 ing to this author, they are 



always quite spherical in 

 the living cell and run to- 

 gether on the death of the 

 cells, for example, on heat- 

 ing to 70 C, into large 

 drops which change into 

 beautiful crystals of sul- 

 phur. This crystallization 

 takes place best when Beggi- 

 atoa threads rich in sulphur 



FIG. 18. i. Beggiatoa threads, a, very rich 

 in sulphur; l>, after 24, c, after 48 hours' cul- 

 ture in spring- water; s, granules of sulphur. 

 nlppprl for ahniif a mtn 2 - The same > 2 4 hours after treatment with 



picric acid, which largely converts the sul- 

 phur globules into crystals. After Wino- 

 gradsky. 



ute in a concentrated aque- 

 ous solution of picric acid 



and then washed in a large quantity of water. On such 

 threads beautifully formed sulphur crystals were found after 

 twenty-four hours, partly monoclinic prisms and partly rhom- 

 bic octahedra (cf. Fig. 18, 2). It is therefore to be presumed 

 that these sulphur grains consist of the modified form of 

 sulphur which is semi-fluid or oil-like at ordinary tempera- 



