β-propiolactone-treated dorsal lips ofAmbystoma mexicanum are grafted in the blastocele of young gastrulas. The inducing ability of dorsal lips is not altered. These results are compared with the effects of formaldehyde which suppress the inducing ability. An interpretation of these facts is proposed. The cross-linking reactions which occur between formaldehyde and proteins may be important for the suppressing of the inductive ability by this agent.