This study was concerned with establishing the changes in pattern of protein synthesis associated with graft formation in Lycopersicon esculentum Mill., using a dual labelling technique. The mechanical strength of the graft was used as a parameter of development. Mechanical strength was found to be related to both cell number and number of tracheary elements for breaking weights up to 130 g after which it was related to tracheary element number alone. The transition between two stages occurred 3-4 days after grafting. The ability of a graft to form in isolation was investigated. It was found that a graft could develop in culture for at least twenty-four hours after excision without significant change in the pattern of development.