Motility - it is the movement ability of bacteria from one direction to another by themselves. Some bacteria are motile and some are non - motile. So the answer - is in normal slide motility of bacteria can be haulted by pressure of coverslip on slide. So to overcome this problem hanging drop method is used. For details consult pharmapathway .com --motility --hanging_
Hello, the bacteria that show no motion are termed non-motile. However, in an aqueous environment, these same bacteria appear to be moving erratically. This erratic movement is due to Brownian movement which results from the random motion of the water molecules bombarding the bacteria and causing them to move.