When I left that night, my box of clippings occupied its usual place on the office floor. By the next day it had vanished. A month's worth of newspaper and magazine reading -- the lovingly collected scraps I cling to for reference and inspiration -- was lost.

The night janitor, I deduced, had thrown them out. I wanted him punished. Instead, the incident became my belated introduction to the realities of a labor market awash in immigrants.

None of the people who work in modern high-rise offices like mine are less visible than the night janitorial crew. Newspaper people often work late, so I occasionally encountered someone pushing a cart into my office to remove the mounting debris. There were small reminders of nighttime visits. During basketball season, the office television was often set on the Laker channel when I arrived the next morning.

But seen or unseen, the janitors in my building in Century City, a clump of offices sprouting from an old Hollywood back lot, always left a clean office and never mistook my precious clippings for trash. Whenever I saw them they had a smile and a kind word. And they spoke excellent English.

But they were members of the Hospital and Service Employees Union Local 399 and no match for 1 million Latin Americans crossing the border every year. The union and Pedus Building Services, the firm that employed them, tried to save the cleaning contract by agreeing to cut the wage and benefit package from about $8.80 to $6.80 an hour, but it was too late.

Unbeknownst to most tenants, the building's management put the contract up for bid, and Benco Building Services won it. Its workers, at least half of them Spanish-speaking immigrants, would receive $4 an hour, paid holidays and two weeks vacation but no health benefits.

"Buildings all over Century City are going nonunion," said building operations manager Jill Clements. "It worked for them, so we thought it would work for us."

My office colleague, Kathy Macdonald, and I had expressed our displeasure over the missing clips in vivid terms. The new janitor, we were told, was as unused to our office routine as he was to the language, but someone would make certain it would not happen again.

Coming through the lobby very late one evening, I saw the building's night supervisor struggling to explain a vacuuming chore to a smiling, uncomprehending immigrant. Yet, Clements said "there have been far fewer complaints than we expected."

Supervisors for Benco and Pedus said they check to see that their immigrant employes have the "green cards" that prove their legal residence and give them the right to work in the United States. But the supervisors said there is no way of knowing if the cards are genuine or not.

Like the British during the raj, like Americans living abroad today in several dozen Third World countries, we Californians whose jobs are relatively safe from the immigrant deluge -- and that includes most of us -- appreciate the advantages of cheap labor.

I read of Washington legislators and lobbyists decrying the destruction of American organized labor by unregulated workers from the south. The problem is real, but here it raises surprisingly few hackles.

A Pedus executive said the company maintains some union contracts, despite its setback in Century City. Some building managers prefer to pay more for the assurance that a higher-paid union crew will stay with the job and learn their tenants' idiosyncracies. My building kept the union crew on the day shift, probably because they were more highly skilled in maintenance and familiar to the tenants.

The executive said the change worried him but noted that Pedus employs crews in buildings throughout the West, many of them nonunion. Union official Dave Stillwell said most of the workers will bounce back: The young will find other jobs in this still-expanding labor market and get by on lower wages and benefits.

"But for the ladies in their late 40s and early 50s, it's going to be tough," he said.

My brief annoyance at the change has passed. I was unable to locate any of the workers left unemployed by the switch. No major California election in the last two decades has hinged on immigrant threats to jobs. The new workers help keep my office rent low and inflation down.

A century ago mobs burned the San Francisco docks where ships tied up to disgorge more cheap labor from China. But those days, like my box of clippings, are gone forever. Jay Mathews