Undergraduates directing this spring's semi-annual blood drive are trying to decrease the percentage of students who sign up but fail to donate.

Gail E. Gabler '81, director of the undergraduate drive said yesterday about 40 per cent of the 1700 potential donors who signed up last fall did not actually donate.

She added that recruiting for the drive--which will last from April 4-11--began Monday and will continue until next Wednesday.

Volunteers are working at each house and the Freshman Union to recruit donors and answer questions; and faculty, graduate students and staff members are soliciting donors by mail, Gabler said.

She added that recruiters are trying to increase participation in the drive by stressing the need for blood and easing students' fears of donating.

Gabler said people are often willing to sign up, but are afraid to show up.

Volunteers are handing out fact sheets at their recruiting stations emphasizing the safety and simplicity of the procedure, Gabler added.

John S. Scheft '80, director of promotion for the drive, said yesterday recruiters are tying to encourage contributions from those who have not previously participated.

People who have already given blood know that it is not painful and that it "gives the donor a tremendous amount of satisfaction," Scheft added.

Dorothy Reiss, deputy director for the Cambridge Red Cross--which supplies the technical staff and equipment for the drive--said yesterday that although many programs still pay donors, most Red Cross organizations do not.

"Some donors tend to be less honest when giving their medical histories for money rather than purely altruistic reasons," she added.

"It's one of the only charities that is free," Scheft said, adding "Giving blood is pure altruism."