Determined diffusion coefficients (μm² s^–1)for each probe in flagella (D_fl) and aqueous solution(D_aq). D_fl values are means ±s.d. (N=6). D_aq values were determined by extrapolating the plots as in Fig. 3 (N=3, see the text for more details). The ratios, D_fl/D_aq, are also shown