Several undergraduates who experienced severe physical and psychological reactions after ingesting illegal drugs purchased in Cambridge have caused University administrators to fear an increased distribution of marijuana and LSD laced with harmful synthetic hallucinogens.

During exam period two students were treated and released after they smoked marijuana purchased on campus that they believe was "dusted" with either angel dust, the alcohol extract of marijuana, or PCP, a synthetic amphetamine derivative also used as a horse tranquilizer, Archie C. Epps III, dean of students, said yesterday.

Dr. Paul A. Walters Jr., chief of psychiatry at the University Health Services, said yesterday that although no cases of treated marijuana have been brought to his attention, there is evidence of an alarming reemergence of "bad acid," especially LSD laced with speed derivatives such as PCP.

Take Sominex Tonight

Walters said the reaction to drugs treated with PCP is similar to an overdose of Sominex, a commercial sleep-inducing drug.

Mack I. Davis II, director of advanced standing, said yesterday that several students he heard about reported feeling "very frightened, unsafe, out of control and speedy" reactions atypical of the usual effects marijuana induces.

Davis said the increasing pervasiveness of "street drugs" (amphetamine derivatives synthesized in a laboratory) has resulted because "enough students in our community are indiscriminate in their choice of drugs."

Bad Stuff

"We are not talking about a new wave of drug abuse at Harvard, but there is enough bad stuff being sold around metropolitan Cambridge that students should be very cautious about who they buy drugs from," Davis said.

He added that even experienced marijuana smokers cannot predict their reactions to "dusted grass."

Walters said that students coming to UHS are "talking about drugs again--more than the last two or three years," adding that this was a warning of trouble to come, especially if those who sell impure LSD, the most common street drug, step up their dealings.

The Last To Know

Walters said that even if students know their source, they probably have no idea where the drugs are coming from originally and cannot distinguish the subtle differences between grades of LSD.

The pushers "might have good intentions, but there is no quality control--it's a seller's market because we cannot regulate illegal substances," Walters said.

Walters, who for five years taught a course in the College called "Drugs and Adolescence," said that despite a myth that certain varieties of marijuana are much stronger than others, the natural plant varies only a little in THC content.