In some of the pioneering papers on the magneto‐ionic theory, certain misleading or incorrect statements regarding the polarization of ionospheric radio waves have appeared, apparently leading to a misunderstanding on the part of later workers. The notion that the ordinary and extraordinary ellipses should have mutually perpendicular major axes is not, in general, correct, being applicable only in the case in which the collisional friction of the electrons is neglected. It is the purpose of this paper to clarify this poin