BACTERIA. 
27 
flagella in one species— Bacillus, and all without 
flagella in another species— Bacterium. 
When for any reason there comes a period of hard Spores 
times in the life history of the bacteria, such as cold, 
dryness, or lack of food, some bacteria have the 
(a) A flagellum at one end. 
(b) A flagellum at each end. 
(c, d. and e) Tufts of flagella in different positions. 
(After Conn.) 
power of contracting their bodies into smaller space, 
possibly drawing it all into one end or from the mid¬ 
dle into each end. Fig. 17. This is called the spore 
stage. These spores can weather great extremes of 
famine or cold or resist the action of strong chem¬ 
icals. Some can be frozen, others boiled and still re¬ 
tain life. When good times return in the form of 
