Il6 ESSENTIALS OF BACTERIOLOGY 



method may be used: (i) Smear and fix as usual; (2) stain 

 with hot carbolfuchsin for two minutes, pour off the surplus 

 dye without washing; (3) counterstain and decolorize by 

 pouring five times over the preparation the following solu- 

 tion: A i per cent, alcoholic solution of corallin is saturated 

 with methylene-blue and 20 parts of glycerin added. Wash 

 in water, dry with blotting-paper, then in the air, and exam- 

 ine. The tubercle bacilli are stained red, smegma bacilli, 

 blue. 



Examination of Milk for Tubercle Bacilli. Place a drop 

 of the sample on a cover-glass and mix it with two drops 

 of a i per cent, solution of sodium carbonate. The cover- 

 glass is then gently warmed until evaporation is complete. 

 The saponified fat is then stained, as the ordinary cover-glass 

 preparation. Only a few tunes has any one succeeded in 

 discovering the bacillus in milk. 



Other Acid-fast Bacteria. The bacillus of leprosy re- 

 sembles the tubercle bacillus in its staining properties, but 

 gives up the carbolfuchsin more easily and is usually de- 

 colorized by the acid and alcohol. It is colored blue by Pap- 

 penheim's method. 



Acid-fast bacilli have also been obtained from timothy 

 grass, butter, milk, manure, and the surfaces of animal bodies, 

 but differ from the tubercle bacillus in cultural characteristics. 



Water has been found to contain acid-fast bacilli; care 

 should be taken to test the water used previously to any im- 

 portant examination for tubercle bacilli. 



Biederfs Method of Collecting Bacilli. When the bacilli 

 are very few in a great quantity of fluid, as urine, pus, abun- 

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

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

 sodium hydroxid, then boiling until the solution is quite 

 thin. It is placed in a conical glass for two days, and bacilli 

 with other morphologic elements sink to the bottom of the 

 glass; when the 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. 



