METHOD FOR STAINING FLAGELLA 93 



the slide with carbol-fuchsin until the stain " rounds 

 up." 



5. Heat the under side of the slide directly, with a flame 

 until the carbol-fuchsin steams (but not boils). Keep the 

 stain steaming for five minutes. 



6. Wash in water. 



7. Decolorize by dipping the slide preparation into 

 20% H2SC4 for an instant and washing immediately. This 

 process may have to be repeated two or three times. If 

 not careful, however, the tubercle bacteria may be decolor- 

 ized. If this happens, their acid-fast property will be 

 destroyed to some extent. 



8. Counterstain with aqueous-alcoholic methylen blue. 



9. Wash in water, dry and examine directly with the 

 oil immersion lens. The specimen, if a good one, may then 

 be mounted in the usual way without removing the immer- 

 sion oil. 



EXERCISE 31. METHOD FOR STAINING FLAGELLA 



Flagella, the exceedingly delicate organs of locomotion 

 of bacteria, cannot be seen in an unstained or in an ordinary 

 stained preparation. Special staining methods must be 

 employed to make them visible. They are generally ren- 

 dered visible by precipitating some chemical on them; 

 this generally increases their width considerably. 



The staining of the flagella of bacteria is the most 

 difficult of all bacteriological procedures and it generally 

 requires considerable practice to insure good results. 



There are many methods for staining flagella. This 

 one, however, has met with considerable success with stu- 

 dents. Failure to make a good flagella stain with any 

 method is no sign that the student is not a good work- 

 man, nor is success the sign of a good bacteriologist. 



Apparatus. Clean glass slides; absolutely clean cover- 

 glasses; small platinum loop; several cover-glass forceps; 



