t 750 ] 



stance or tissue should be done in the fresh state, and if the 

 suspicion is confirmed, permanent mountings should be made 

 and expert opinion sought in the matter.' 



1.297. A. drop of the fluid or the substance to be mounted 

 is taken up with a clean glass rod or tube, or better still 

 with a bit of sterilised platinum wire, and spread over thin 

 on a number of cover glasses. These are first air-dried and 

 then passed rapidly through the flame of a spirit lamp or 

 Bunsen burner, taking care that the side of the cover-glass 

 with the film of the substance treated, is on the upper side. 

 The prepared cover-glasses are then put in a dyeing solution 

 for different periods of time, say, two for 5 minutes, two 

 for 10 minutes, two for one hour, and two for 24 hours. 



1.298. A very good staining solution to use is the Ziehl- 

 Neelson solution which consists of one part of Fuchsin, 

 ten parts of absolute alcohol and one hundred parts of a 

 five per cent, aqueous solution of Carbolic acid. The 

 Fuchsin is first dissolved in the alcohol and the carbolic 

 acid solution is then added to it. The solution should be 

 kept in a non-actinic stoppered bottle. 



1.299. Another good staining solution is Loffler's Alkaline 

 Methylene Blue. This consists of 30 parts (in volume) of a 

 concentrated alcoholic solution of Methylene Blue and 100 

 parts of a *oi per cent, solution Caustic potash. 



1.300. Gentian violet and Fuchsin Red are the two com- 

 monest stains in use. 2 to 5 grammes of either of these 

 aniline dyes are taken and rubbed up in a mortar with 10 

 C. C. of absolute alcohol, and then gradually 90 C. C. of warm 

 distilled water are added while proceeding with the rubbing. 

 The solution thus made should be kept in a non-actinic 

 stoppered bottle. 



1.301. When the film on the cover-glass has been under 

 the dye for a certain period (which is different with different 

 bacteria), the bacteria take the dye. The excess dye on the 

 cover-glass is washed away first with distilled water (with 



