To the Editor : Alfred Kazin, in reviewing Scott Donaldson's biography of Archibald MacLeish (July 12), is right to be cautious in this statement: "The 600-page F.B.I. file on [ MacLeish ] , Mr. Donaldson tells us, is the longest on any American writer.
There is a much larger F.B.I. file on Wilhelm Reich, which has been referred to in the literature. There is an equally huge file on Herbert Marcuse, which to my knowledge has not yet been utilized. A file of approximately 600 pages is available about Erich Fromm, which remains unexplored. And it will come as no surprise that Lillian Hellman and Dashiell Hammett have considerable dossiers.
If Mr. Donaldson were to take a narrow, biological view of what constitutes an American writer, I think it worth pointing out for the sake of readers and scholars that several hundred F.B.I. pages are extant about Walter Lippmann. No one has explored in print the information about Lippmann that J. Edgar Hoover collected.