SAN CRISTOBAL, CUBA -- This town 50 miles west of Havana has seen Cuba's future, and it is bleak.

At the Comandante de Pinares Hospital, they are using homemade thread for sutures made from henequen, a cactus-like tropical plant. In a small garden out back, they're growing medicinal plants to treat dozens of illnesses.

At the El Mango farm, a five-minute drive outside town, there are similar efforts at self-sufficiency under way: Oxen are replacing broken-down tractors in the fields, and all animal feed and fertilizer are locally produced.

And not far away, a food-generating project has been launched to breed the jutia, a rodent whose meat was popular with Caribbean Indians in pre-colonial times. Dictionaries say the jutia is a rat; Cubans say it's actually quite tasty once you get used to it.

Designated at the start of the year as Cuba's laboratory of the future, San Cristobal has been transformed into a dress rehearsal for national survival in an increasingly hostile world.

"We don't know what's going to happen with the Soviets next week," said agro-engineer David Morales, a Communist Party official in the town of 63,400. "It requires us to prepare for the worst."

The worst, as President Fidel Castro has frequently reminded Cubans this year, might not be far off.

He has said that preparations have begun for a "special period in peacetime" -- a drastic austerity program that would freeze all social programs. Construction of schools, hospitals, day-care centers and homes would halt as the island shifted to something resembling a wartime economy.

The austerity program has been publicized exhaustively in the military press, leading Western diplomats here to surmise that it would be supervised by the military. The idea would be to save hard currency to spend on essential imports such as petroleum and to preserve economic development projects such as road-building and dollar-generating tourism ventures.

Talk of the "special period" has alarmed many Cubans. But diplomats say that even without a formal declaration, Cuba may find itself in a special period as the nation's stagnant econonomy turns sickly.

The economy slowed from a 2.2 percent rate of growth to barely 1 percent last year, and prospects for this year are worse still.

But the real pinch is expected to begin in January, when the Soviet Union has said it will adjust all international trade to eliminate subsidies and reflect real international prices.

Cuba's trade with the Soviet Union amounts to about 70 percent of its overall international commerce. To ease the impact on the Cuban economy, which has already been buffeted by Eastern Europe's political upheaval, the Soviets are negotiating a special arrangement with Cuban officials to phase in the new policy. Nonetheless, Moscow's new posture may cost Cuba as much as $150 million in lost subsidies in 1991, according to foreign diplomats in Havana.

Cuba, like most islands, has always been a dependent society -- first on the Spanish during the colonial era, then on the United States until the 1959 revolution, and since then on the Soviet Union. With domestic pressure building in Moscow to reduce Soviet assistance, Cuba for the first time in its history faces the daunting prospect of forced, if gradual, independence.

"The whole sense is that for the first time, they're not on the crest of the wave; they're about to be swamped by it," said a Western diplomat. "The image of the invincibility of the regime has evaporated. How {Castro} deals with the current economic crisis will be the supreme test of his leadership."

Already there are signs of strain in the economy. Shipments of spare parts for buses, which used to come from Hungary, have been suspended. Certain automobile parts, never easy to find in Cuba, have become scarcer still. Food-packaging materials are also said to be in short supply.

In Havana's La Playa neighborhood this week, nearly 100 people stood in line for the chance to buy pineapples and plantains. In a market next door, there was next to nothing to buy on the shelves -- no canned meat, no vegetables, no bread, no rum, no vodka and no condensed milk. The only dairy product available was fresh milk, which is rationed.

In the rear of the store, about 50 people waited for their rations of chicken. Cubans are allotted a pound of chicken about three times a month. They watched through a window as two butchers, with cigarettes dangling from their mouths, hacked the poultry into one-pound portions.

Castro has acknowledged the hardship, blamed it on the U.S. trade embargo and what he calls Eastern Europe's political "disaster," and called for sacrifice.

But he has also assured people that the Cuban social safety net of educational, medical, child care and other services will not be allowed to fray. Even if Cuba is forced to scrap construction programs for social services for five or 10 years, it would still be able to offer world-class programs in those areas, he declared in a speech Thursday.

As he has throughout his 32-year rule, Castro blames the United States for Cuba's problems. But in recent months he has turned up the rhetoric several notches, suggesting that the United States had virtually laid siege to Cuba and could attack at any time. By raising the threat of U.S. aggression, he apparently is seeking to justify his calls for deeper sacrifice and to prepare people psychologically for such sacrifice.

To an extent, the strategy appears to be working. While there is widespread discontent with living standards, many Cubans seem to believe that the United States is considering an attack on the island. The inauguration of TV Marti, the U.S. government's project to beam programs into Cuba, and last December's U.S. invasion of Panama have served to buttress Castro's warnings.

In addition to playing on Cubans' fierce nationalist sentiments, Castro is working to halt Cuba's economic isolation in several other ways. He has pursued an ambitious expansion of Cuba's tourism industry and pushed for higher trade levels and closer diplomatic ties with China and Latin America.

Cuba's trade with China has doubled in the last three years to about $500 million this year. And Cuba has also been successful in finding a market for its medical exports, such as meningitis B vaccine, in Brazil. However, most economists say that Cuba's potential for export expansion in Latin America is limited, both by the kinds of products it has to trade and by its lack of access to credit.

Although Castro has ruled out any structural changes along the lines of the Soviet Union's perestroika, pressure appears to be building to tinker with the rules under the guise of "perfecting" the socialist system.

Preparations are under way for the Fourth Communist Party Congress early next year, a once-in-five-years event that has been mentioned repeatedly as a potential watershed. Cuban intellectuals say they are pushing for greater freedom for individual initiative, such as renewal of the brief experiment in farmers' markets that Castro abolished.

There is little sign that Castro's regime intends to embark on significant reform at the congress; nonetheless, many Cubans are hopeful that it could create its own momentum, particularly as expectations rise.

The authorities "say they want a change," said one professor at the University of Havana. "But they want it to be a controlled change, a moderate change, a directed change. That may not be enough, but it's all we have to work with."