MICBO-OEGANISMS. 



STAINS. 



In the investigation of micro-organisms the following solu- 

 tions of the Aniline Stains and of the Intermediate Eeagents 

 are employed. 



Different samples of the same aniline dye will differ in their 

 behaviour to solvents. Some will make a clear solution, 

 others will leave more or less insoluble residue. The solu- 

 tions should therefore be filtered or decanted. It is safer to 

 filter aqueous solutions each time before use. 



Aqueous Solutions of the dyes do not keep well, therefore 

 Alcohol has been added as a preservative. 



(i.) VESUVINE (Bismarck Brownk. 



(a) Glycerine Solution. Saturated ^solution in equal 

 parts of Glycerine and Distilled Water. 



(b) Aqueous Solution. Yesuvine, 1 grm. ; Rectified 

 Spirit, 20 cc. ; Water, 80 cc. 



(ii.) METHYLENE BLUE. 



(a] Saturated Alcoholic Solution. 



Methylene Blue, 15 grms.; Absolute Alcohol, lOOcc. ; shake 

 at intervals for one or two days until saturated, then filter. 



Only a small percentage of the dye is soluble in Alcohol, yet the depth 

 of colour obtainable in the solution increases in proportion to the quan- 

 tity added up to 15 p. c., but not further. 



(b) Aqueous Solution. Methylene Blue, 1 grin. ; Recti- 

 fied Spirit, 20 cc. ; Distilled Water, 80 cc. 



