That wild flower known as ""experimental writing,"" which used to be the emblem of any collection of ""modern"" poetry and prose, has pretty much either been uprooted or trimmed. At least that's the impression Philip Rahv's anthology, ""representative of present trends in literature and criticism,"" conveys. For the most part, the offerings here do not evince any interest in stylistic innovations, nor is the subject matter in any sense radical. The hip, snappy, slightly strident tales of Irvin Faust or Mordecai Richler, with their slurpy heroes and all too sophisticated touches of black humor, seem refugees from Esquire. Thalia Selz' long, wryly feminine, sweet-and-sour account of the trials of the emancipated woman is a typical Partisan Review product. And Stephen Sohmer criss-crosses between Cheever and Albee in a neatly constructed, ironic study of a failed marriage. The poetry, aside from A.R. Ammons' specimens, is efficient, here and there touching, but hardly worth a second look. And Stephen Donadio's essay-survey of the younger poets is simply graduate school respectability. What established figures like Robert Brustein, Maurice Cranston, John Barth, and Robert Lowell are doing here, given the premises of the collection, is hard to fathom. With the exception of Lowell's excellent Juvenal re-working, these gentlemen are not up to their reputation. German's Hans Enzenberger and Holland's Karel Van Het Reve are trenchant observers of the international culture scene. And there are two skittery domestic farces with the obligatory Ionesco influence. A rich, but unadventurous, gathering with more fiction than non-fiction predominating.