Criticism of Kurylowiez' development of the theory that IE ǝ was a consonant. His studies have led to a number of acceptable etymologies; but these can be explained on the earlier assumptions, while a number of others are inconsistent with the theory, which as a whole cannot be maintained. Hittite h is the continuant of an Indo-Hittite consonant that was lost in Indo-European.
E. H. Sturtevant (Sun,) studied this question.
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