28 MANUAL OF MICROBIOLOGICAL METHODS 



3. Pour off solution A, and without washing add solution B, also through 

 a filter, and allow it to stand 7 min without heating. 



4. Wash with distilled water. 



5. Before the slide dries, cover with ZiehFs carbol fuchsin (page 13), 

 allowing it to stand 1 min on a hot plate heated just enough for 

 steam to be barely given off. 



6. Wash in tap water. 



7. Dry in the air, and examine. 



Results: Similar to the preceding methods, but the background pre- 

 cipitate is usually finer and less conspicuous, thus interfering less with the 

 demonstration of unusually fine, delicate flagella. 



Staining flag ella of anaerobes. O'Toole (1942) calls attention to cer- 

 tain difficulties in staining the flagella of anaerobes and gives a modifica- 

 tion of the above Bailey stain which is intended to overcome them. The 

 method is not unlike that of Fisher and Conn, who had the O'Toole pro- 

 cedure in mind when working out their modification. 



CAPSULE STAINS— RECOMMENDED PROCEDURES 



Bacterial capsules are more easily confused with artifacts than any 

 other structure pertaining to the organisms. Inasmuch as capsules 

 sometimes show merely as unstained areas around the cells, there is a 

 temptation to call any such surrounding area a capsule; very often, how- 

 ever, they merely represent the tendency of a lightly stained surrounding 

 medium to retract from the cells on drying. For this reason the best way 

 to demonstrate capsules is actually to stain them by some procedure which 

 differentiates them from the cell itself. Several of the flagella stains 

 accomplish this, notably those of Bailey and Leifson, given above. 

 Much simpler is the procedure of Anthony described below. The 

 Anthony method can be recommended because of both its simplicity and 

 its dependability. Any of the other methods which follow give satis- 

 factory results. The student is specially urged, however, not to pro- 

 nounce any organism capsulated, as a result of any of these staining 

 procedures, until he has carefully compared it with other organisms 

 generally recognized as having capsules. 



Leifson Method 

 Leifson {1930) 



This method is described in detail above (page 27) and does not need 

 to be repeated here. The special methods of handling slides and cultures, 

 outlined for flagella staining, do not need to be observed, but the following 

 is essential: 



