120 MICRO-ORGANISMS AND DISEASE. [CHAP. 



bacilli if the preparation is stained after Ehrlicli's method. 

 About 5 com. of pure aniliu (aiiilin oil) are well mixed with 

 100 ccm. of distilled water and filtered ; to this is added a 

 saturated alcoholic solution of fuchsin, and with this the pre- 

 paration is stained for a quarter to half an hour. It is then 

 washed for a few seconds in a mixture of one part of nitric 

 acid and two parts of water, and then is w T ell washed in 

 distilled water. The preparation when now examined 

 shows no trace of colour except in the tubercle-bacilli, which 

 retain the red colour of the fuchsin. The tissue may now be 

 stained ei i her with vesuvin or methylene-blue, which makes 

 the groundwork brown or blue, but the bacilli remain red. 

 This reaction after washing with nitric acid is exceedingly 

 delicate, and is perfectly characteristic and trustworthy, as all 

 putrefactive organisms become discoloured by the washing 

 with nitric acid, the tubercle-bacilli only retaining the colour. 

 There are other methods which are very good ; those of Wei- 

 gert and of Gibbes l are very quick and trustworthy in their 

 action. 



Weigert has devised a staining fluid which gives very beau- 

 tiful results and is very useful for staining sections, fresh or 

 hardened ; it is as follows : Take of a two per cent, watery 

 solution of gentian- violet 12 ccm., and of a saturated watery 

 solution of anilin oil 100 ccm. Mix. This is used like an 

 ordinary staining-fluid for the first stain. For the second or 

 contrast stain the following solution is used : 



Bismarck brown . . ... 1 gramme. 

 Spiritus vini rectificati (sp. gr. -830) . 10 ccm. 

 Distilled water ..... 100 ccm, 



The sections remain in a few drops of this solution for fifteen 

 minutes. This method yields the finest specimens of tubercle- 

 bacilli in sections through tuberculous growths that I have 

 seen ; unfortunately the colour of the bacilli is very liable 

 to fade. 



In the case of tuberculous sputum, or similar matter, a 

 small droplet or particle is spread out in a thin layer on the 

 cover-glass, well dried by passing it over the gas-flame of a 

 Bunsen burner, and then stained in the way described in 

 Chapter I. Sections of tubercles, fresh or hardened, are 

 stained without first drying. 



In all cases of human tuberculosis, particularly in the spu- 

 tum, in caseating scrofulous glands, in bovine tubercles, in 

 artificially-induced tubercles and caseating glands of rodents, 



1 Lancet, August 5, 1853. 



