10 BACTERIOLOGY. 



elongate and gradually assume its original shape, or 

 the bacillus may form inside the body of the spore and 

 burst the capsule. (See Fig. 9.) 



Motiiity Th e p 0wer of .locomotion is observed in some 



bacteria. When watched under the microscope they 

 may be seen moving across the field of vision. The 

 motility depends upon small, threadlike processes pro- 

 jecting from the bodies of the bacteria, called flagella 

 (singular form, flagellum), which by moving to and 

 fro with a whiplike 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 bac- 

 terium. The motility of spirilla is somewhat differ- 

 ent. The amount of protoplasm about the nucleus is 

 much more abundant than in the bacilli, and this by 

 an undulating, wavelike motion drives the organism 

 forward. The phenomenon of locomotion is limited to 

 bacilli and spirilla; the cocci do not move. (See 

 Fig. 6, page 57.) 



The property of producing pigment or coloring 

 matter is peculiar to some kinds of bacteria. The 

 pigment may be entirely within the body of the 

 organism or it may be set free from it and color the 

 ^e s pe of material upon which the bacteria are growing. Other 

 bacteria 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 important 

 of all, and will be; spoken of in detail in the chapter on 

 immunity. 



