12 MICRO-ORGANISMS AND DISEASE. [CHAP. 



For other methods to stain tubercle-bacilli see the chapter 

 on the latter. 



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 minutes, are then washed in water, 

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

 solution or Dammar varnish. 



5. Lustgarten's 1 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 oil gentian- 

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

 alcohol, and then transferred to a 1*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 

 quite colourless. Only the syphilis-bacilli, tubercle-bacilli 

 and leprosy-bacilli, are able to retain the dye ; other 

 bacteria lose it by being subjected to the permanganate. 



De Giacomi 2 has improved this method of decolourising 

 by oxidation. Cover-glass specimens made of syphilis material 

 are stained with warm fuchsin for a few minutes, are then 

 washed in water to which a few drops of solution of iron 

 perchloride have been added, then placed into concentrated 

 solution of iron perchloride till the preparations have lost all 

 colour; they are then stained for contrast in vesuvin or 

 Bism arck-bro wn. 



1 Lustgarten, Med. Jahrbiicher der K.K. Ges. d. Aerzte, Vienna, 1885. 



2 De Giacomi, Schweizer Correspondezblatt, xv. 12. 



