LIKE A DYNASTIC line that weakens with every succeeding generation, Frank Herbert's latest work, The Dosadi Experiment, owes its prominence more to its ancestry than any distinguishing strength of its own. Dune, with its meticulously laid-out setting and equally convincing set of characters, proved that Herbert is the ultimate practitioner of the fantasy-science fiction art. As the best fantasy sci-fi should, it ensnarls its readers; entrapping the unsuspecting alien in a coherent, make-believe world that he can escape only when the author permits it, with his final page.

After reading Dune, sci-fi fans were convinced Herbert could do no wrong--sadly, though, he fails to maintain such heights in his following books. Perhaps Dune reached heights no author could reclimb. Sensing a mesmerized readership, Herbert continued with Dune Messiah and Children of Dune, well-crafted books but not quite on the same level as their forebearer. Dosadi uses many of Dune's conventions and provides some entertainment, but the reader no longer believes he is holding the ancient, jewel-encrusted dagger in his hand and is chanting the mystical incantations.

Dosadi is the name of a barren planet, isolated from the rest of the universe by a "god-wall" from an unknown source, the Calebens. (No Shakespearian connotations, as they are good guys.) Outside of Dosadi's wall is a complex universe with a tenuous power balance among humans, the frog-like Gowachins and the death-dancing wreaves--with their Kung-fu-like movements and poisoned mandibles. Jorj X. McKie, a red-haired man of Polynesian descent, is the only human accepted as a Legum in the Gowachin legal system. Herbert fails to give the legal cult the depth of Dune's Bene Gesserit witches but he still shows traces of his creative genius:

They provided ways to kill any participant--judges, Legums, clients.... But it must be done with exquisite legal finesse, with its justifications apparent to all observers, and with the most delicate timing. Above all, one could kill in the arena only when no other choice offered the same worshipful disrespect for Gowachin Law. Even while changing the Law, you were required to revere its sanctity.

McKie has divided loyalties as he is also the most feared agent of the universe's counterweight to the Gowachin order, the Bureau of Sabotage, a cross between the CIA and the Texas Rangers. McKie, in a previous book, gained the power to communicate with the Calibens who, in actuality, are the stars. His special Caliben protector is Fannie Mae.

IN WHAT WILL give Herbert fans a feeling of deja vu, Dosadi, with its poisonous ecology, holistically breeds a supremely cunning civilization. The Gowachins established a colony there to observe human development. The densely populated city Chu is under constant siege from the desperate people of the "rim," who are exposed to the brunt of the planet's hardships. Their only chance for species survival is to breed uncontrollably.

Herbert brings in potentially captivating ideas: the fantasy version of a Malthusian crisis and the clash of two omnicompetent cults both of which are the playthings of a greater power. However, he fails to develop them beyond the elementary stages. The lifestyle of those doomed to live on the rim goes unexplored when it could be the most graphic part of the book. Herbert only touches on the training it takes to be a Legum, how the newly indoctrinated members shed their skins (that is much easier for a frog to do than a human.) Herbert should initiate the reader into his Elysian mysteries but instead, he just whispers a few riddles.

Some of Herbert's scenes are masterful, and only further frustrate the reader by showing how well Herbert can write. A conversation between McKie and a Gowachin takes on the intensity and precision of military strategy. With a minimum of narration and a taut dialogue, the scene provides one of the book's few gripping passages.

The romance between McKie and the female Keila Jedrick, the most cunning of the hostile planet's products, is the book's focal point. Though the two have their good moments, especially when they unite their minds, this relationship fails to carry the book with the necessary emotion.

Dosadi accepts a Darwinian order where the male Gowach weeds out his weakest offspring at birth. The planet itself allows only the strongest to survive and then hones their capabilities to the keenest point, preparing them to infiltrate and alter the universe that spawned their world. If publishers were to apply the same rigors to Herbert's books, Dosadi would be the first of his progeny sacrificed. It is a competent work of fantasy but Dosadi is not what the faithful fan expects of Frank Herbert.

He spends too much time detailing individual maneuverings and fails to create a convincing atmosphere of intrigue and mysticism. There are religious fanatics, homosexual kamikaze warriors, and Fannie Mae, but Herbert does so little with them. Too often he leaves the reader teased with his imagination but unfulfilled with his writing. Dune is a book that pleased all, from fantasy freaks to History and Lit majors, but Dosadi is only for the most dedicated sci-fi readers.