Fig. 4. Effect on the internal contraction ratio of the length of time between the first flush of the organ bath and the addition of the second dose of 2x10^-5 mol l^-1 5HT. Note the scale break between 3 and 24 h. Values are means ± 1 S.E.M., N= 18 (15 min), 98 (30 min), 41 (60 min), 8 (2 h), 4 (3 h), 15 (24 h).