Competence and Sequential Induction in Presumptive Epidermis of Normal and Hybrid Frog Gastrulae

the induction of various cell types from the presumptive epidermis of Rana pipiens gastrulae have led to formulation of the concept of sequential induction (Barth and Barth, 1963; 1964; Barth, 1964). By increasing the length of treatment with lithium chloride, different cell types are induced. Since during the treatment with the inductor the presumptive epidermis continues to develop, the question of the role of changing competence with age arises. How much of the sequence of inductions may be attributed to the inductor and how much to a possible sequence in competence? This paper deals with the change in competence with respect to time in the presumptive epidermis of normal gastrulae, and also includes a comparison of the competence of normal and hybrid presumptive epidermis.