10 
' BACTERIOLOGY. 
Proper¬ 
ties of 
bacteria 
jecting from the bodies of the bacteria, called flagella 
(singular form, flagellum), which by moving to and 
fro with a whip-like motion propel the bodies forward. 
The flagella may be single or multiple, and may be 
placed at one or both ends or all around the bacterium. 
The motility of spirilla is somewhat different. The 
amount of protoplasm about the nucleus is much more 
abundant than in the bacilli, and this by an undulating, 
wave-like motion drives the organism forward. The 
phenomenon of locomotion is limited to bacilli and 
spirilla; the cocci do not move. (See Fig. 7 , page 61 .) 
The property of producing pigment or coloring 
matter is peculiar to some kinds of bacteria. The pig¬ 
ment may be entirely within the body of the organism 
or it may be set free from it and color the material 
upon which the bacteria are growing. Bacteria exhibit 
variations in the way they stain with aniline dyes. 
Some will resist the action of dyes unless they are 
applied hot and then they will not give up the stain if 
exposed to the action of decolorizing solutions; the 
tubercle bacillus is a notable example. Solutions con¬ 
taining iodine (Gram’s solution) also fixes the stain in 
some bacteria. These are spoken of as being Gram 
positive. Other properties of bacteria that may be 
mentioned are the fermentation of sugars into alcohol, 
the production of characteristic odors, the formation 
of acids and alkalies, and the production of light. The 
property of producing poisons is perhaps the most im¬ 
portant of all, and will be spoken of in detail in the 
chapter on immunity. 
