BACTKRIA. 



PRELIMINARY. 



Mix some India ink or jmely powdered gam- 

 boge with water and examine a drop with a 

 high power. 



Note that when the currents in the water have 

 ceased the particles of gamboge do not move 

 from place to place. 



Now observe the vibration or oscillation of the 

 lifeless particles (Brownian movement). 



BACTERIA. 



I. Active Bacteria. 



Examine with the highest power a drop of hay 

 infusion or of other liquid containing active 

 'bacteria. Observe : 



1. Form. 



2. Size. (Measure). 



3. Structure. ( What points of structure are vis- 



ible ?) 



4. Movements. 



(a) Brownian movement. 



(b) Active movement from place to place. 

 Treat with iodine. 



Does the iodine bring out any details of 

 structure. What is its effect upon the 

 movements of the bacteria? 



45 



