52 LABORATORY BACTERIOLOGY 



EXERCISE XX 



STAINING THE FLAGELLA ON MOTILE BACTERIA 



79. The motile bacteria are provided with a variable num- 

 ber of long, hairlike appendages or flagella. These are invisi- 

 ble in the fresh preparation, and they do not stain by the 

 ordinary methods. By special staining processes, however, 

 their presence can be detected. Several methods have been 

 proposed for staining these filaments, but nearly all of them are 

 based on the use of a mordant. Curiously enough the value 

 of each of these methods seems to rest largely on the skill of 

 the individual ifsing them, as some workers succeed with one 

 method while others fail with it but obtain excellent results 

 with one of the other processes. Although the flagella are 

 known to be the organs of locomotion, they do not seem to be 

 of any special morphological value in differentiating closely 

 related species. They are, however, elements in the structure 

 of motile bacteria, and their demonstration is much to be 

 desired. 



References. — Chapters on staining flagella in standard text- 

 books. Moore, A Review of the Methods, etc., Am. Monthly Mic. 

 Journal, Vol. XIL (i89i),p. 15. Moore, The Character of Flagella, 

 etc. Wilder, Quarter-century Book, p. 339. Loeffler, Centralblatt f. 

 Bakteriologie, etc., Bd. VI. (1889), S. 209. Ferrier, Archives de 

 Mdd. Exp. et d'Anat. pathologique, T. VII. (1895), p. 58. Van 

 Ermengem, reviewed in Centralblatt fur Bakteriologie, etc., Bd.XV. 

 (1894), No. 24. 



80. Work for this Exercise. — Make a cover-glass prepara- 

 tion from the growth on the agar culture of Bacillus cholera 

 suis made in Exercise XVII. and stain it with carbol fuchsin. 

 Preserve this to compare with preparations stained for the pur- 

 pose of demonstrating the flagella. 



Clean about 20 cover-glasses after the special method for 



