352 Tuberculosis 



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 granular 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 fragment 

 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 

 immersed, smeared side up, in a small dish of Ehrlich's 

 anilin-water gentian violet solution : 



Anilin 4 



Saturated alcoholic solution of gentian violet 11 



Water 100 



and kept in an incubator or paraffin oven for about twenty- 

 four hours at about the temperature of the body. Slides 

 upon which smears have been made can be placed in Coplin 

 jars containing the stain and stood away in the same manner. 

 When removed from the stain, they are washed momentarily 

 in water, and then alternately in 25-33 P er cent, nitric acid 

 and 60 per cent, alcohol, until the blue color of the gentian 

 violet is entirely lost. It must be remembered that the 

 action of the strong acid is powerful, and that too long a 

 time must not be allowed for its application. A total 

 immersion of thirty seconds is enough in most cases. After 

 final thorough washing in 60 per cent, alcohol, the specimen 



