Fig. (4) Increment in the mass of the tunic which the mechanical stimuli were put on (Δmr). A, Siphon (n = 6); B, M1 (n = 6); C, M2 (n = 3); D, Bottom (n = 5). The dotted lines indicate Δmr when the mechanical stimuli were applied to the specimen just after the mass was measured at Day 1.