Twenty years ago Hendrik Verwoerd, the South African prime minister who was assassinated in 1966, devised the concept, which is still government policy, of establishing separate tribal homelands in which most of the country's blacks eventually are supposed to live apart from whites.

Since the plan was put into practice, however, the number of blacks in the main part of the country has continued to increase as South Africa's expanding industrial economy has required their labor.

Now Verwoerd's son is reversing his father's idea and trying to establish a kind of homeland for whites, where they can live completely apart from blacks.

Hendrik Verwoerd Jr., a 42-year-old former minister of the Dutch Reformed Church, is full-time secretary for an organization called the Oranjewerkers (Orange Workers) that wants to stake out parts of the country where whites can free themselves from all dependence on black labor.

They must do their own housework and sweep their own streets. The working day must be extended by an hour so managing directors can clean their own offices, mail their own letters and deliver their own messages.

In South Africa, where cheap black servants are part of the white way of life, the idea is revolutionary.

The thinking behind it is that only if the Dutch-descended Afrikaners, who after three centuries here regard themselves as an indigenous "nation," can have a place where they are not outnumbered by the general black majority can they be ensured national survival.

The Orange Workers are a fringe organization, and at this stage there is little prospect of their plans being taken seriously by the government.

But they have important connections within the Afrikaner establishment that dominates the white-run political system. One important supporter is Verwoerd's brother-in-law, Carel Boshoff, chairman of the powerful Broederbond secret society.

The Orange Workers are also connected to the South African Bureau of Racial Affairs, a conservative think tank on race policy.

Increasingly, too, the organization is associating itself with the fast-growing new Conservative Party on the far right, which showed itself to be a potential threat to the government when it came close to winning a key by-election Aug. 18.

Should the Conservative Party ever gain power, the Orange Workers' plan could find legislative backing.

In the meantime, it is a revealing oddity, a caricature of the Afrikaners' racial behavior. It reveals, however, the depth of their survival imperative in a continent where they are heavily outnumbered but which they cannot leave without losing their identity.

The Orange Workers take their name, said Verwoerd, from William of Orange, the symbol of Dutch freedom in the struggle against Spanish domination in the 16th century.

The Afrikaners, he said, face a similar struggle against being swamped by blacks.

By the year 2020, Verwoerd noted, whites will be only 10 percent of the total South African population, and Afrikaners are only 60 percent of the whites.

If they remain thinly scattered among the masses who outnumber them, he said, they will be powerless and, in time, will disappear.

But if they concentrate themselves in particular areas, they will be able to retain their identity like the Basques and the Scots, said Verwoerd.

Yet the Orange Workers are not really a defensive group, shrinking into a refuge and giving up the Afrikaners' claim to a larger South Africa. In one breath Verwoerd talks of concentrated pockets for future survival; in the next he talks of Afrikaners spreading their influence over the whole country.

He does not like the word "homeland" for his concept. It is too limiting. He talks of "growth points," by which he means points from which the system can grow until it includes all 87 percent of South Africa that falls outside the black homelands. The whole country must eventually free itself of black labor, he said.

And the black population, which by the year 2020 will number about 80 million, must be self-sufficient in the tiny, as yet undeveloped tribal homelands.

"Our whole purpose is to be realistic," said Verwoerd. "We must get away from the purely theoretical and help whites face up to the practical implications of the policy of separation."

His concept, he says, is not really a reversal of his father's. Rather it is an extension of it.

"The various peoples of South Africa must be disentangled. Each must have his own national area. That is the only way national groups can associate peacefully with each other. Otherwise there will always be competition and conflict between them."

The Orange Workers have earmarked three growth points for the start of their project. One is a narrow arc about 100 miles long curving to the south of Johannesburg. A second, somewhat longer, straddles the Orange River separating the Orange Free State and Cape Province. The third is a narrow coastal strip stretching about 275 miles west of Port Elizabeth.

The idea now is to imbue Afrikaners with the ideal of white self-sufficiency and persuade them to settle in these areas. Verwoerd says the organization would like legislation prohibiting blacks from being employed there.

To spread the word there is a newsletter, Oranje, sent to the organization's 1,000 paid-up members and 5,000 other important Afrikaners.

It propagates the idea in emotive terms, exhorting Afrikaners to revive the spirit of their pioneering days and to sacrifice luxury for the sake of national security.

It carries readers' letters exchanging advice on how to kick the habit of living with servants--everything from the wondrous discovery of the dish-drying rack to how to organize local schoolchildren into a lawn-mowing service.

One contributor, Mrs. J.H. Knoetze, of Messina in the far northern Transvaal, writes how her farmer husband has built a low, squat house with cement beds, chairs and dining table. All very practical, she says. Everything within reach, no dust, no polishing and no getting down on your knees to clean under things.

Verwoerd was slightly abashed when asked who cleaned his office in central Pretoria.

"One is part of a system," he said defensively. "We rent the offices and they are serviced -- unfortunately by blacks."

It is different at home, though. On weekends Verwoerd lives with his wife, five children and 82-year-old mother at a luxury retreat on the banks of the Vaal River south of Johannesburg that an Afrikaans newspaper company gave to his father when he was prime minister.

Weekdays he stays in Pretoria with his sister, Anna, and her husband, Carel Boshoff.

Neither home has a servant, even though the Vaal retreat has nine acres.