THE METHODS OF STAINING MICROBES 81 



twenty-four hours in a strong aqueous solution of 

 inethylene blue ; and finally treated in the usual 

 way. (3.) 'The best method yet described of de- 

 monstrating the cholera bacillus in the discharges 

 of the intestines is that recommended by Cornil 

 and Babes, who spread out one of the small white 

 mucous fragments on a microscopic slide, and then 

 allow it to dry partially ; a small quantity of an 

 exceedingly weak solution of methyl violet in dis- 

 tilled water is then flowed over it, and it is flat- 

 tened out by pressing down on it a cover-glass, 

 over which is placed a fragment of filter paper, 

 which absorbs any excess of fluid at the margin 

 of the cover-glass. Cholera bacilli so prepared 

 and examined with an oil-immersion lens 

 (Zeiss' ^o homog., Oc. 3 or 4) may then be seen ; 

 their characters are the more readily made out 

 because of the slight stain they take up, and 

 because they still retain their power of vigorous 

 movement, which would be entirely lost if the speci- 

 men were dried, stained, and mounted in the 

 ordinary fashion/ 



For staining cover-glass preparations of the blood 

 of patients suffering from relapsing fever (i.e. con- 

 taining the Spirillum Obermeieri), fuchsine, gentian 

 violet, and Bismarck brown have been used with 

 considerable success. Sections of the brain, liver, 

 lungs, kidneys, etc., of monkeys or human beings 

 dead of the disease, are best stained with Bismarck 

 brown, vesuvin, or chrysoidine. 



Cover-glass preparations of the blood, exuda- 

 tions of the throat, etc., from cases of scarlatina 



F 



