34 PRACTICAL BACTERIOLOGY. 



This liquefied fluid is allowed to stand for 12 to 24 

 hours in a conical urine glass, and the sediment exam- 

 ined. Or a portion of the liquefied sputum may be 

 centrifuged and the sediment examined at once by the 

 usual methods. In urine, smegma bacilli give staining 

 re-actions allied to those of the bacillus of Tuberculosis. 

 If the Ziehl-Neelsen process is accurately carried 

 through, only rarely will there be danger of mistaking 

 smegma bacilli for Tubercle bacilli. Sudan III is 

 however, a positive differential stain. 



When microscopic methods fail, inoculation of a 

 guinea pig subcutaneously or intraperitoneally, will lead 

 to the development of Tuberculosis, if any living bacilli 

 are inoculated. 



