APPENDIX B. 

 ON THE STAINING OF "BACILLUS TUBERCULOSIS." 



PROFESSOR KOCH (Verh. Physiol. Gesell., Berlin, 1882, p. 65) 

 first announced the discovery of the Bacillus of tuberculosis. 

 He placed the fluid from the diseased tissues in a mixture of 



1 c. cm. of a concentrated solution of methylene blue in alcohol, 

 o'2 c. cm. of a ro-per-cent. solution of potash, and 200 c. cm. of 

 distilled water. By this the preparation is coloured blue, and a 

 few drops of a solution of vesuvin are then placed on it. This 

 discharges the blue from every part except the Bacilli, which 

 remain blue in a brown field, but are not easily seen. 



Ehrlich's method, especially as modified by Heneage 

 Gibbes, is more successful. The colours used by the latter 

 are magenta crystals and chrysoidin, which is a brown that 

 does not stain the ground so intensely as vesuvin. (i) Take 



2 grm. of magenta crystals, 3 grm. of pure aniline, 20 c. cm. 

 of alcohol (specific gravity, 830), 20 c. cm. of distilled water. 

 Dissolve the aniline in the spirit, and rub up the crystals with it 

 in a glass mortar, adding the spirit gradually till they are all 

 dissolved ; then add the water slowly, while stirring, and keep 

 in a stoppered bottle. (2) Make a saturated solution of 

 chrysoidin in distilled water, and add a crystal of thymol to 

 make it keep. (3) Make a dilute solution of commercial nitric 

 acid, one part of acid to two of distilled water. Spread a thin 

 layer of sputum on a cover-glass, and let it dry ; when quite dry 

 pass it two or three times through the flame of a small Bunsen 

 burner, and let it cool. Filter two or three drops of the magenta 



