94 STUDY OF BACTERIA 



3. Wash well in water. 



4. Dry and pour on "B" for thirty seconds. 



5. Wash, dry and mount. 



The protoplasm of the bacilli will be stained brown, and the 

 characteristic (diagnostic) chromatin points will be stained a deep 

 blue black. 



Tubercle Bacillus Stain. 



1. Spread the sputum, pus or culture, over the surface of the cover-slip. 

 Allow the preparation to thoroughly dry. 



2. Fix in flame and cool. 



3. Pour carbol-fuchsin over the slide and heat with steaming for five minutes. 

 Young bacilli in tubercles and other fluids are very difficult to stain in this way. 

 The preparation containing them should be stood in cold carbol-fuchsin for 

 twenty-four hours. This method stains everything on the slide. 



4. Wash hi water. 



5. Decolorize the preparation with a 25 percent solution of sulphuric acid 

 in water until the red color is lost. Repeat this once or twice. 



6. Wash and counterstain with Loffler's methylene blue. 



7. Dry and mount. 



In such a preparation, if tubercle or other acid-fast bacilli are 

 present, the bacilli will be colored a brilliant red, while the pus cells, 

 epithelial cells, and other bacteria will be stained blue. 



The ultra microscope dark field illumination enables one to see 

 flagella and capsules. This illumination is obtained by blocking 

 out the central portion of the Abbe condenser in the substage of 

 the microscope. Light is admitted only from the sides and objects 

 in the field at the point of crossing of the rays reflect these from 

 their sides. India ink may be used as a background for bacteria 

 that stain poorly and have low refractive index. 



Protozoa are stained by Wright's method in one of its various 

 forms. Microscopic objects are measured by viewing with an 

 ocular fitted with a graduated glass disc. Their values are indi- 

 cated on the apparatus. 



