3 i o Tuberculosis 



sequently modified Koch's method, showing that pure 

 anilin was a better mordant than potassium hydrate, and 

 that the use of a strong mineral acid would remove the 

 color from everything but the tubercle bacillus. This 

 modification of Koch's method given us by Ehrlich is the 

 best method of staining the bacillus. 



Staining the Bacillus in Sputum. As the purpose for 

 which the staining is most frequently performed by the 

 physician is the diagnosis of the disease by demonstrating 

 the bacilli in sputum, that method will be first described. 



If one desires to make a very careful examination, it is 

 well to have the patient cleanse the mouth thoroughly upon 

 waking in the morning, and after the first fit of coughing 

 expectorate into a clean, wide-mouthed bottle, the object 

 being to avoicj the presence of fragments of food in the 

 sputum. 



A better result will be secured if the examination be 

 made on the same day, for if the bacilli are few they occur 

 most plentifully in small flakes of caseous matter, which are 

 easily found at first, but which break up and become part 

 of a granula*r sediment that forms in decomposed sputum. 



The sputum should be poured into a watch-glass and 

 held over a black surface. A number of grayish-yellow, 

 irregular, translucent fragments somewhat smaller than the 

 head of a pin can usually be found. These consist prin- 

 cipally of caseous material from the tuberculous tissue, 

 and are the most valuable part of the sputum for ex- 

 amination. One of the fragments is picked up with 

 a pointed match-stick and spread over the surface of a 

 perfectly clean cover-glass or slide. If no such frag- 

 ment can be found, the purulent part is next best for 

 examination. 



The material spread upon the glass should not be too 

 small in amount. Of course, a massive, thick layer will 

 become opaque in staining, but should the layer spread be, 

 as is often advised, "as thin as possible," there may be so 

 few bacilli upon the glass that they are found with diffi- 

 culty. 



The film is allowed to dry thoroughly and is then passed 

 three times through the flame for fixation. 



Ehrlich' s Method, or the Koch-Ehrlich Method. Cover- 

 glasses thus prepared are floated, smeared side down, or 



