STAINING FLAGELLA. 25 
(7) Examine the hanging-drop preparations of 
the last section in reference to this movement. 
Do they all show the Brownian movement? Are 
some actively swimming about, changing their 
position in relation to one another ? All bacteria 
exhibit the Brownian movement, but certain ones 
are motile of themselves. They possess organs of 
locomotion or flagella, lash-like appendages, by the 
movements of which they propel themselves along. 
The flagella may be very numerous, extending 
from all sides of the cell, or they may be collected 
in a tuft at one end, or Hieie may be a single one or 
a pair (periecichous, lophotrichous, monotrichous, 
amphitrichous). The flagella may be demonstrated 
by appropriate methods of staining. 
Ill. Staining Flagella. 
1. Pittield’s Method. 
(2) Prepare a mordant as follows: 
Tannic acid (10 per cent. solu- 
tion, filtered), 10 C.c.3 
Corrosive sublimate (saturated 
aqueous solution), 5¢¢. 3 
Alum (saturated aqueous solu- 
tion), 5 ee, 5 
Carbol-fuchsin ' 5 Gc. 
Allow to stand and draw off the clear fluid. The 
mordant will keep one or two weeks. 
1 See Appendix, page 172. 
