Four years ago, Paula Lozano '84 entered Harvard with a clear vision of what she wanted to do when she left.

"My original plan was to become a science researcher I was turned on by DNA and I thought it would be pretty cool to study it for a career," Lozano recalls. But after the Dunster House resident graduates today, she will instead head to South America and work at several public health centers.

"My plans have changed enormously," she says, "primarily because of my experience in laboratories."

Lozano is one of the approximately 150 undergraduates who work in the Harvard science laboratories, in Cambridge and at the Medical Area in Boston. They serve as apprentices for faculty members, either doing theses, independent projects, or work-study research during the school year or summer.

Many students say they find the lab work--a field usually dominated by graduate students--rewarding even if it does not completely fit into future plans.

"It's very exciting to be in a lab, to see things work out, and you can learn an enormous amount from the people around you there," Lozano says of her four years in labs both at the Med School's Department of Microbiology and the Cabot Science Complex's Bio Labs, studying bacterial viruses.

"But I think I realized that the kind of person I was needed more interaction with people. At this stage in my life I have to explore before choosing a career," the Biochemistry concentrator adds, pointing out, however, that she will probably devote part of the future to some kind of medical research.

John F. Dowling '57, associate dean of the faculty for Biological Sciences, says this kind of trial and error is an important reason for getting students to work in the labs.

"You have to see what research is all about and how different it is from courses," he says, adding that many find it discouraging. Some undergraduates, he comments, realize "this is not what I am. It is a lonely occupation where answers are difficult to come by and there are lots of pratfalls.

But for many students, college lab work is just a prelude to similar career pursuits. David Perkel '84 has spent much of the last two-and-one-half semesters, including last summer, studying the brain's visual processes at the Medical School's Neurobiology Department.

Next year, Perkel will study similar neurobiological aspects at a French national research institution in Lyon, partly because of a close working relationship with former Med School Professor of Neurology Simon Le Vay.

"The nature of the experiments [including some 30 hour straight operations on animals] took two people. Working directly with him, I learned everything front the expert," Perkel says.

For Marvin Appel '84, his thesis lab work on mouse leukemia cells was the highlight of his academic career at Harvard. "It makes you think and see science as it really is," he says of the hands-on experience. "Lectures tend to be reduced to more simplicity than it really is." Appel will enter the Medical School next year for a combined Ph.D./Md. program and intends to go into non-laboratory physiological research after graduation.

Lab work is important even for future scientists who do not choose to do their work in that type of setting, says Terry Deacon, director of the anthropology labs. "If students are going to work in the scientific field it's invaluable that you know about the laboratory field even if you are not going to work in labs," he adds.

Deacon points out that almost 50 percent of next year's senior class in his department will have done some kind of lab work under the auspices of a faculty member. A higher percentage is expected the year after, he says, in part because officials feel the lab work is becoming more important for the field.