Turmoil is spreading in China as student demonstrations - the biggest since communists seized power in 1949 - call for more democracy, for human rights, for a free press and for an end to official corruption.

There may be some tendency to blame this unrest on looser controls and the free market reforms begun in China a decade ago, especially since the economy is in such bad shape. But China's problems stem from too little reform, not too much.The market-oriented reforms actually produced an unprecedented upsurge in rural production and wealth. But along with that upsurge, there has been a growth in corruption among communist officials in cities, villages and national offices all over China.

Well-entrenched, old-party bureaucrats felt threatened by the changes begun a decade ago and have resisted them at every turn. With decentralization, local officials not only have power to resist but have grabbed the chance to enrich themselves.

As a result, some of the worst habits of the old pre-World War II China have returned. As one reformer explains, "Everything is for sale - children's places in good schools, proper medical treatment, scarce raw materials for industry," and bribery of every imaginable kind is rampant.

How extensive is the corruption? Observers say it is deeply rooted and involves not only party officials but their children and families as well. An estimated 20 percent of the national income is going into the pockets of corrupt officials. No nation can prosper in such circumstances.

The corrupt officials also have hampered existing economic reforms and kept others from being enacted.

The answer to China's problems is not a return to tight party control. In fact, at this point it may be impossible for an aging party leadership to assert that kind of absolute authority. Too much of the party apparatus is in the hands of those very same corrupt bureaucrats.

A free press, guarantees of human rights and other steps toward democracy would put pressure on corrupt officials. Such steps should be encouraged. Educated young people are either looking for ways to get to America or have taken to the streets to demand change.

The demonstrating students probably lack enough clout by themselves to bring about significant change, but if the economy gets bad enough, the turmoil could spread to other parts of the population.

China is reaching some critical crossroads. What happens in the coming months may tell if the country will be able to pull itself into economic stability in the 1990s or whether it will slowly collapse into conditions more resembling the 1920s.