90 BACTERIOLOGY 



acid has been added (1 drop to 50 grms. water). After 

 staining, the sections are rinsed in water, decolorised in 

 iodine and potassium iodide solution, transferred to absolute 

 alcohol, treated with aniline oil and with xylol, and preserved 

 in Canada balsam. 



Tlnna's borax methyl blue method. — A process which is 

 particularly to be recommended for tubercle and lepra 

 bacilli is the treatment of the sections for 5 minutes with 

 aqueous borax methyl blue, from which they are transferred 

 for 5 minutes more to a 5 per cent, solution of potassium 

 iodide to which a crystal of iodine has been added. 

 Einsing in alcohol follows until a blue cloud forms, and 

 then differentiation in creosote, lasting from a few seconds 

 to half an hour, according to the intensity of the staining. 

 The sections are afterwards transferred to rectified oil of 

 turpentine, in which the bluish colour immediately changes 

 to red or brown, and are put up in a solution of colopho- 

 nium in oil of turpentine. 



XJnna's method of demonstrating the organisms of the skin. 

 • — Unna has devised several methods for staining micro- 

 organisms in furuncles and abscesses of the skin, which 

 can also be used to show the micro-organisms of pus. In 

 all these methods the sections are previously stained in 

 carmine and treated for two minutes with borax methyl 

 blue (1 part each of borax and methyl blue in 100 of water), 

 after which [in the Jirst method] they are rinsed in water 

 and placed for a few seconds in a 1 per cent, aqueous 

 solution of arsenic acid, then in alcohol, bergamot oil, and 

 balsam. 



According to a second method the sections, after a slight 

 preliminary staining with carmine and methyl blue, are 

 brought for five to ten seconds into a 20 per cent, solution of 

 ferrous sulphate, then into alcohol so long as any colour 

 comes away, then for some seconds into a 1 per cent, solu- 



