(biology, of bacteria) Having a single flagellum on each of two opposite ends. (Only one flagellum operates at a time, allowing the bacterium to reverse course rapidly by switching which flagellum is active.)
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It is found, however, that strict reliance cannot be placed on the distinction between the Monotrichous, Lophotrichous and Amphitrichous conditions, since one and the same species may have one, two or more cilia at one or both poles; nevertheless some stress may usually be laid on the existence of one or two as opposed to several - e.g.