MOTI LIT Y CAPSULES 



Motility of bacteria. A large number of bacteria pos- 

 sess the power of movement, accomplished by means of 

 cilia or jluji-lla, forming spiral processes, of which some- 

 times one is present, sometimes several, and which keep 

 up an incessant vibration. 



This motility must not be confounded with oscillatory 

 movements (also, however, to be understood as originated by 





FIG. 1. FORMS OF B.\< TKHIA. Magnified about 700 times. (After Baumgarteu.) 



the bacteria themselves), nor with such motion as occurs in 

 inert particles suspended in a fluid medium, and which is 

 known as the 'molecular movement of Brown ' (Brown inn 

 increment). 



Capsules of bacteria. Capsules are formed by swelling 

 of the membrane, and are best seen in those micro- 

 organisms which are found in groups viz. the diplococci, 

 streptococci, tetracocci, and sarcinae ; but various bacilli 

 also, such as Pfeiffer's capsule-bacillus and the Bacillus 



n 2 



