306 BACTERIOLOGY. 



before death, a more important role than the associated 

 bacteria. 



The great majority of stained smears from specimens 

 of sputa show not only the tubercle bacilli stained in 

 red, but many other bacteria stained blue. Some of 

 these associated bacteria have come from the diseased 

 areas of the lungs, while others were merely added 

 to the sputa as it passed through the mouth, or have 

 developed after gathering. To separate the one from 

 the other we wash the sputa. 



Sputum Washing. The first essential is that the 

 material be washed within a few minutes, and certainly 

 within an hour, of being expectorated. If a longer 

 time is allowed to intervene, the bacteria from the 

 mouth will penetrate into the interior of the mucus, and 

 thus appear as if they came from the lungs. Sputum 

 treated twenty-four hours after its expectoration is use- 

 less for examining for anything except the tubercle 

 bacillus. A rough method is to pour some of the speci- 

 men of sputum to be examined into a convenient re- 

 ceptacle containing sterile water, and withdraw, by 

 means of a sterilized platinum wire, one of the cheesy 

 masses or thick " balls' 7 of mucus. Pass this loop five 

 times through sterile water in a dish; repeat the oper- 

 ation in freshwater in a second and third dish. Spread 

 what remains of the mass on cover -glasses and make 

 smear preparations; stain and examine. With another 

 mass inoculate ascitic bouillon in tubes and agar in 

 plates. 



If it is desired to examine the specimens for capsule 

 bacteria, pneumococci, etc., they may be stained by 

 Welch's acetic-acid method (page 203) or by Gram's 

 method (page 203). 



