Appendix 1—figure 3. Effect of polarization on response amplitude.

After its tip links had been broken by exposure to 5 mM BAPTA for $30\mathrm{s}$, a hair bundle from the bullfrog’s sacculus was stimulated in the negative direction with 50 ms, 30 mW laser pulses. Using a half-wave plate between the laser and the coupling optics, we rotated the polarization plane about the axis of propagation between 0 and 50. For a simple polarized object, the reflected power should decline by the cosine of the angle. Although the results showed a qualitative agreement with the prediction, we observed a significantly smaller reduction in amplitude consistent with the fact that stereocilia are birefringent, but exhibit significant scattering of light at all angles. Each trace represents the average of 25 recordings.