抄録
The classification of growth twins into contact and interpenetration twins is critically discussed based on kinetic consideration. It is shown that all growth twins are originally contact twins. If re-entrant corner effect operates throughout whole growth process, the twin develops as a contact twin. If the habit changes during growth, or two individuals conjugate on different faces, it develops to an interpenetration twin. No interpenetration twins are expected from their start, except for a case when growth occurs on high temperature form which consists of twinned domains due to phase transition.
