Flagellar waveform reversal in Euglena

Films taken during experiments on the electrical control of flagellar motion in Euglena and of control by microinjection were analysed for the occurrence of the reversal reaction of the flagellar waveform. In all cases it was found that an induced decrease in flagellar frequency is accompanied by an increased fraction of the cells showing flagellar reversal. A plot of the flagellar frequency vs the percentage flagellar reversal shows that for all experimental methods of inducing a change the relation between flagellar frequency and reversal is identical. This indicates that flagellar frequency and waveform reversal in Euglena are controlled through one common intermediate.