I went back to school the other day -- actually it was an alumni convention held a hundred miles south of my old hilltop campus. Lincoln University in Jefferson City, Mo. It was like a family reunion -- a coming together of siblings from far-flung places who had grown up in a community where our development was carefully nurtured. But Lincoln had changed a lot, and it left me uneasy. I'm not sure I like it.

Once all-black, its student body now is more than one-half white, as are its faculty and staff. I'm not arguing against its integration; I just don't want it disintegrated. Colleges like Lincoln are worth preserving, but that effort is in trouble. Lincoln's total desegregation is a unique answer to the hotly debated question of the future of predominantly black colleges.

Thousands of men and women in Washington today owe their success to a black college somewhere in their past, and these institutions have spawned much of the country's black leadership. Had Martin Luther King not attended Morehouse as well as Boston University, he might be alive and mediocre today.

More than 40 percent of this nation's black bachelor's degree holders got their degrees from historically black colleges. And although only one-fourth of black students were enrolled in black institutions in 1978, half the college degrees they earned were granted by black colleges.

That's in part because the dropout rate among black students at predominantly white schools is 60 percent. It isn't that the standards at black colleges are lower, it's that many blacks come from systems that ill prepare them, so a student may be bright but academically inadequate. The black college takes him where he is and tries to move him to where he should go. These schools are great for what they do with what they get.

Lincoln's existence is owed to the soldiers and officers of the Civil War-era 62nd and 65th U.S. Colored Infantry who gathered $6,000 to begin a school to train and educate blacks in Missouri. Its history is tied to preserving black heritage and achievement. There is a story like that behind nearly any black college in the country.

When I transferred to Lincoln as a junior to study journalism because my predominantly white Catholic all-girl school did not offer it, that heritage and tradition socked me in the eye. Scholarly professors, most of them black, from Ivy League colleges and other top schools around the country, were there, bent on making Lincoln a "black Amherst." They were role models of excellence, preparing us academically and psychologically to enter the mainstream.

We weren't from the country's black elite but from average black working families of ministers and teachers and day workers, where the spending money often came $2 at a time folded inside envelopes addressed in awkward script.

While black colleges thus are far from perfect, you must credit their educating many people who would not otherwise get within a stone's throw of a college. They'd have no chance at shedding second class citizenship or contributing to the diversity that distinguishes America today.

All that heritage is today being threatened. "What I'm trying to do is hold the line," says James Frank, the reedy, youngish president of Lincoln and a Lincoln alumnus. "Whites would like us to forget . . . what Lincoln meant to blacks for over 100 years."

He faces an almost classic dilemma of maintaining some semblance of black continuity in a time when racial integration is the official watchword in education. Even unofficial attempts to keep traditionally black colleges going are now being thwarted by budget restrictions that make it hard to justify funding two separate schools or systems that are supposed to do essentially the same thing.

Frank has felt the pulls and tugs of the dilemma in many ways:

He recently sat through a long trial brought about when a white professor sued the university, charging it discriminated against him when the university tried to hire one black professional in an all-white sociology department. "At times I felt like crying," said Frank, "at times I felt extreme anger." The professor lost the case.

For years, reporters regularly have asked if he felt it was time for Lincoln to have a white president, given the changed character of the school. "Why don't you ask the University of Missouri if it isn't time for a black president," he'd snap. Until recently, Lincoln was the only institution of higher learning in Missouri where blacks served in administrative positions. "They wanted to take that away from us, too," he said.

The brain drain all black colleges have felt stings deeply, for Lincoln is neither fish nor fowl -- all white or all black, and it cannot compete with higher salaries offered by larger, more prestigious institutions.

White alumni lack the pride in the institution that blacks have. Many are older commuters or state workers and do not involve themselves in campus life. Some even deny they are Lincoln graduates.

Alumnus Thomas B. Shropshire, who now is senior vice president and treasurer of Miller Brewing Company, told the group the historically black colleges are a key to helping blacks achieve 1980 style economic parity. "If we do not see that our young people receive the skills they will need to compete in the world of the future, by the year 2000, fully half of those born in 1979 can expect to be unemployed."

It may be hard to understand just where we are coming from. But like the black church, the black college transmits an atmosphere, a heritage, a culture, an anguished/joyful past. They're not for everybody, but there'll be a need for them as long as there's a need for Notre Dame or Brandeis University.