86 BACTERIOLOGY 



Combination of staining methods. The dyes are selected 

 in the same manner as when staining the bacteria from a 

 plate-culture or from a mixed mass of them ; and the com- 

 bination of several colours is indicated, because then that 

 of the bacteria stands out distinctly from the ground tint 

 of the tissue. 



Kiihne's methyl blue method, Kiihne, to whom the most 

 marked advances in the technique of staining are due, re- 

 commends as the most reliable method the staining of the 

 sections with methyl blue dissolved in a 5 per cent, carbolic 

 acid or a 1 per cent, ammonium carbonate solution. In 

 order to differentiate the preparations, they are brought after 

 staining into a weak aqueous solution of lithium carbonate 

 or into slightly acidulated water, then dehydrated in abso- 

 lute alcohol to which some methyl blue has been added, 

 and transferred to aniline oil, similarly mixed with methyl 

 blue. Each section is then cleared by immersion in pure 

 aniline oil, next in a light fluid etherial oil, such as that 

 of thyme or terebene, and finally in xylol, and is mounted 

 in balsam. 



For staining the bacilli of tuberculosis, leprosy, and 

 mouse - septiccemia a method may be used which differs 

 from the foregoing only in the substitution of fuchsine for 

 the methyl blue. 



Koch's method. The sections after staining are trans- 

 ferred to a saturated solution of potassium bicarbonate 

 which has been diluted with an equal volume of water, and 

 thence to alcohol, cedar oil, and Canada balsam. 



Lbffler's method. Loffler stains the sections in an alka- 

 line solution of methyl blue, decolorises in half per cent, 

 acetic acid, and thence brings them into absolute alcohol, 

 cedar oil, and Canada balsam. 



Chenzynsky's Method. The sections are immersed in a 

 methyl blue and eosine solution containing forty parts con- 



