In fact it's in the sidebar "Combinatorial tone-row' (what a mouthful, and what is it, anyway) but he's not guided there.  Or told that it begins and is mostly sustained as a cello line - as in, curiously, an almost exactly similar juncture in Strauss's Don Quixote, not to mention Delius' Appalachia.  (Schoenberg knew quite a bit of other contemporary composers' music, though perhaps not much Delius, and at the time of Don Quixote he had not declared war on Richard Strauss)