About 150 demonstrators assembled on the Boston Common yesterday to protest last Thursday's slaying of two black students at Southern University in Baton Rouge, La.

Richard Miller, professor of Philosophy at MIT, addressed the demonstrators. "We can either sit on our mars and let the government push racism," he said, "or we can launch on anti-racist movement which would terrify the people who run this country.

Leon Dickson, a graduate student at MIT, read a statement issued by striking students at Southern University which called for "a nationwide boycott of the educational institutions of America."

The protest was orderly and there was no confrontation with Boston police.

Louisiana Governor Edwin Edwards said yesterday that the officers involved in last Thursday's confrontation used their shotguns to fire tear gain cartridges, which he said were similar in appearance to buckshot cartridges.

"It's perfectly, logical and reasonable that one on the officers could have, in all the excitement, fired the wrong kind of ammunition," Edwards said yesterday.

The tear-gas-clouded confrontation between students and police resulted in the death of two black students. Baton Rouge Medical authorities attributed the deaths to backshot wounds to the two students' heads and shoulders.

Edwards said that he was anxious to restore peace to the Baton Rouge campus, but that he would not consider meeting student demands to fire university president G. Leon Netterville. He also rejected their demand that students be given the authority to hire and fire faculty members.

Prior to yesterday's demonstration, Harvard students met in Philips Brooks House to discuss plans for a mass protest meeting scheduled for Sunday at 7:30 p.m. in Lowell Lecture Hall.