BACTERIA. 



27 



without 



flagella in one species Bacillus, and all 

 flagella in another species Bacterium. 



When for any reason there comes a period of hard 

 times in the life history of the bacteria, such as cold, 

 dryness, or lack of food, some bacteria have the 



a 



FIG. 16. BACTERIA WITH FLAGELLA. 



(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 ons 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 



Spores 



