Prisons: view from behind the bars; In the Belly of the Beast: Letters from Prison, by Jack Henry Abbott. With an Introduction by Norman Mailer. New York: Random House. $11.95.

Who could read Solzhenitsyn on the Soviet prison system and be struck by how lenientm it is? Jack Henry Abbott did -- after spending most of his life since boyhood in American prisons, much of the time in solitary confinement. His indictment of the treatment of prissoners by the authorities, and by each other, is as harsh, profane, and explicit as they come.

His allegations, self-serving though they often are, ought to be part of the debate, as the United States takes up Chief Justice Warren E. Burger's recent challenge to reform its prisons -- in the spirit, it must be hoped, of Winston Churchill's earlier challenge: "The mood and temper of the public in regard to the treatment of crime and criminals is one of the most unfailing tests of any country."

By such a test, America fails abysmally in the eyes of Abbott. He does not condone the crimes committed outside prison. But he seeks to explain some of the worst excesses of the prisoners as rational means of survival in their caged environment. The guards are his particular targets, lending crude and graphic weight to the chief justice's considered view that guards can become part of the problem rather than part of the solution and that a national academy of corrections ought to be established to train prison personnel.

But this book has to be located in literary as well as polemical terms. It began as letters to author Norman Mailer. If the latter's introduction comes unfortunately close to Maileresque romanticization of forceful personalities gone astray, it also recognizes the achievement of Abbott's learning to write under the self-education circumstances of his confinement.

Some of the evocations of this existence recall the harrowing poetry of a Jean Genet. But Abbott's range of reading has not been digested. When he starts judging the political and philosophical landscape beyond the bars, his jumbled notions about communism vs. his own country, for example, betray a mental as well as physical isolation against which his questin g talent will need to struggle.