Fig. 6. Dose—response relationship of red abalone sperm to L-tryptophan. Values are means ± S.E.M. with the regression line calculated using the raw data. (A) Results of a linear regression of log10-transformed dose on sperm swim speed. (B) Results of a linear regression of log10-transformed dose on sperm density. The dose producing the half-maximal response (ED₅₀) was calculated from the regressions to be 3x10^-8 mol l^-1 for both swim speed and cell density.