On the tangentially degenerate curves, II

A projective curve X in ℙ^Nis said to be tangentially degenerate if a tangent line to X at a general point P meets X again at a point other than P. In this article, we prove that if X is tangentially degenerate in characteristic zero, then X is contained in a 2-plane under a certain condition on singularities of X. We also investigate a counter-example of E. Esteves and M. Homma in positive characteristic case, and present a conjecture that our investigation leads to.