PATHOGENIC BACTERIA. 03 



Canada balsam. Examined with oil-immersion. The tubercle 

 bacilli red, all else blue. 



Slaw Method. When perfect permanent preparations are 

 desired and the bacilli to be seen unaltered, the slow method is 

 to be preferred, and it is to be recommended whenever the time 

 allows. It consists simply in allowing the carbol-fuchsin to work 

 upon the preparation a number of hours. We usually place the 

 cover glass with the dried sputum and which has been drawn 

 through the flame three times, in a little dish containing enough 

 dye to allow the glass to be immersed. We do this about 5 or 6 

 o'clock P.M., and the next morning the preparation is ready 

 for decolorizing, the process being the same as described above, 

 viz., 25 % nitric acid, alcohol and water, and the contrast stain 

 methylin blue. We thus avoid the formation of ugly crusts, 

 the bacilli are not distorted, the specimen is permanent and 

 very clear. 



Biederfs Method of Collecting Bacilli, when the bacilli are 

 very few in a great quantity of fluid, as urine, pus, abundant 

 mucus, etc., Biedert advises to mix 15 c.cm. of the fluid 

 with 75 to 100 c.cm. water and a few drops of potassium or 

 sodium hydrate, then boiling until the solution is quite thin. It 

 is placed in a conical glass for two days, and bacilli with other 

 morphological elements sink to the bottom of the glass ; when 

 (he supernatant liquid is decanted, the residue can be easily 

 examined. In this way bacilli were found that had eluded 

 detection examined in the ordinary manner. 



Staining Bacillus Tuberculosis in Tissue (sections}. The general 

 method of Gram can be used, but the better way is to use the 

 following : 



Carbol-fuchsin, 15 to 30 minutes. 



5 per cent, sulphuric acid, 1 minute. 



Alcohol, until a light-red tinge appears. 



Weak methylin blue, 3 to 5 minutes. 



Alcohol, for a few seconds. 



Oil of cloves, until cleared. 



Canada balsam, to mount in. 

 Instead of carbol-fuchsin, alcoholic solution offuchsin or aniline 



