THE ROLE OF SODIUM CHLORIDE IN SEQUENTIAL INDUCTION OF THE PRESUMPTIVE EPIDERMIS OF RANA PIPIENS GASTRULAE

Abstract

1. An analysis of the mode of action of sucrose as an inductor of the presumptive epidermis of the Rana pipiens gastrula leads to the conclusion that sodium chloride is the actual inductor. 2. After treatment with sucrose, induction is proportional to the concentration of sodium chloride in the culture medium. After treatment with sucrose, induction is proportional to the length of exposure to a solution containing 3.4 to 5.15 mg. sodium chloride per ml. 3. It is concluded that sodium chloride in concentrations of from 3.4 to 5.15 mg./ml. is an adequate inductor, while in concentrations from 2.00 to 2.57 mg./ml. sodium chloride does not induce but will sustain the differentiation of various cell types after induction. 4. It is suggested that normal induction by the mesoderm during gastrulation may be brought about by the ions present in the blastocoel. The hypothesis that ions act directly upon DNA complexes has been advanced in a previous paper on induction.