i] MICROSCOPIC EXAMINATION 17 



ing decolourised by the iodine, while another retains the 

 first dye after passing through the iodine. 



3. Ehrlich's method, used specially for demonstrating 

 tubercle-bacilli and leprosy-bacilli. — The specimens, after 

 having been well stained with carbol fuchsin (by heating 

 in a watchglass till the fluid begins to bubble), are trans- 

 ferred for 10-30 seconds into 30 per cent, watery solution 

 of nitric acid ; according to Friedlander a mixture of three 

 parts of nitric acid in 100 parts of alcohol is equally good. 

 A 10 per cent, watery solution of nitric acid is quite 

 strong enough. All bacteria except the tubercle-bacilli and 

 leprosy-bacilli lose the dye by this treatment. The prepara- 

 tions are then stained for contrast in methyl-blue vesuvin 

 or Bismarck-brown. 



4. Koch's method. — According to this the sections, after 

 having been stained, are transferred to a saturated solution 

 of carbonate of potash to which previously an equal volume 

 of water has been added. The preparations remain here 

 for from five to ten mmutes, are then washed in water, 

 alcohol, clove-oil, and finally mounted in Canada-balsam 

 solution or Dammar varnish. 



5. Lustgarten's ^ method, used for the demonstration of 

 the syphilis-bacilli. — The sections are stained for from twelve 

 to twenty-four hours at ordinary temperature, and then for 

 an additional two hours at 40° C. in aniline water gentian- 

 violet ; they are then washed for a few minutes in absolute 

 alcohol, and then transferred to a i '5 per cent, solution of 

 permanganate of potash for ten seconds, then for the same 

 period into a watery solution of pure sulphurous acid ; wash 

 in distilled water, repeat the above process of placing the 

 sections first into the permanganate of potash solution, then 

 into the sulphurous acid water till they become apparently 



' Lustgarten, Med . Jahrbiicherder K. K. Ges, d. Aerzte, Vienna, 1885. 



C 



