"From our point of view there was no migration as such. . . .There was a gradual spread from one center in all directions. In the course of such a spread the groups of dialects and specific isoglosses that had developed were maintained. . . .The biological situation among the speakers of modern Indo-European languages can only be explained through a transfer of languages like a baton, as it were, in a relay race, but not by several thousand miles' migration of the tribes themselves. (152-153)."