Fig. 1. Effect of FK506 on allograft rejection/non-fusion and autograft fusion of transplants from Suberites domuncula. (A) A specimen of S. domuncula also showing the hermit crab Paguristes oculatus. (B) A red and a blue specimen. (C) Graft tied together with a fibre. (D) Beaker in which two grafts are incubated in sea water, as described in Materials and methods. (E–J) In each panel, two grafts are shown that had been incubated in parallel either without (minus; E,G,I) or in the presence of FK506 (plus FK506; F,H,J); the allograft (al) is shown on the left and the autograft (au) on the right. Three different concentrations of the drug were used: 2000ng ml^-1 (F), 200ng ml^-1 (H) and 20ng ml^-1 (J). In I, the fusion zone (fz) in one autograft and the gap (g) in the allograft are marked (arrowheads). E–J were taken 5 days after grafting. Scale bars, 10 mm.