Poetry dissected; Holocaust tale; The Modern Poetic Sequence, by M.L. Rosenthal and Sally M. Gall. New York: Oxford University Press. 508 pp. $29.95; Tzili: The Story of a Life, by Aharon Appelfeld. New York: E.P. Dutton. 192 pp.

''The Modern Poetic Sequence'' is an ambitious critical study which argues that the form ''toward which all the developments of modern poetry have tended'' is ''a grouping of mainly lyric poems and passages, . . . which tend to interact as an organic whole.'' This assertion is defended by analyses of such important works as Thomas Hardy's late, linked autobiographical poems; T.S. Eliot's meditative sequences, such as ''The Waste Land'' and ''Four Quartets''; William Carlos Williams's colloquial ''Paterson''; and Robert Lowell's confessional masterpiece, ''Life Studies.''

General readers may be discouraged by an overabundance of literary terms but will appreciate information about relatively unknown works like Basil Bunting's ''Briggflatts'' and Ramon Guthrie's ''Maximum Security Ward.''

Best of all are two chapters on Ezra Pound, attentive to his innovations and influence and to the problem posed by ''his fascist and anti-Semitic bias.'' In all this is a significant study containing much that will interest readers of 20 th-century poetry.

''Tzili: The Story of a Life'' is the new novel by the acclaimed Israeli author of ''Badenheim 1939'' and ''The Age of Wonders.'' ''Tzili'' is a survival narrative cast in the form of a fairy tale. Its retarded heroine's passage through Nazi-haunted Europe is an allegory of innocence besieged and transformed by evil - appalling, yet not without humanity and hope.