Trailing flagella rotate faster than leading flagella in unipolar cells of Spirillum volutans.

In unipolar cells of Spirillum volutans, the flagellar rotation frequency is halved, approximately, when the flagellar bundle reorientates to rotate about the cell body and reverse the swimming direction. The viscous drag resulting from a concomitant increase in flagellar wave amplitude is probably responsible for the reduced frequency of flagellar rotation.