Harvard has begun a $49 million fund drive to improve facilities for teaching and research in science, the third largest money campaign in the University's history.

The drive opens at a time when money is tight, stocks are low, and potential donors are holding on to their securities. In addition, the University is still looking for well over $100 million in fund drives already under way, including $2.5 million for the International Studies Center.

The Program for Science in Harvard College will not take a back seat to the International Studies Drive, according to President Pusey. Arthur D. Trottenberg, assistant dean of the Faculty for planning and resources, said the two drives seek "different sources, different people."

Big donors are the prime targets for the science drive. A substantial amount would come from federal funds -- perhaps more than half. Corporate money ranks next. "We can't count on nickels-and-dimes contributions," Trottenberg said.

About one-fourth of the money will be used to construct the Science Center, planned for the corner of Kirkland and Oxford St. The Center will include classrooms, laboratories, offices, a library, and computation facilities.

The Departments of Biology, Chemistry, and Physics are all pressed for space, and the Program has special facilities for them. A new laboratory is proposed for the rapidly growing areas of biochemistry and molecular biology.

Also included is a new observatory on Observatory Hill, with classroom space. The Museum of Comparative Zoology will have a new wing added, and the Peabody Museum will be renovated.

The Departments of Mathematics and Statistics, now squeezed into 2 Divinity Ave with the Psychology Department and the Yenching Institute, would find a more spacious home in the Science Center.

Although the main purpose of the drive is to "catch up with faculty growth already achieved," as Dean Ford wrote last June in the Alumni Bulletin, a few additional professorships also have been "reluctantly" included.

Chairman Unnamed

President Pusey will name a chairman for the drive this Fall, and no completion date has been set. At least one University official is pessimistic about the prospects for a campaign of this magnitude, considering that the $82.5 million program for Harvard College ended only six years ago, and drives now in progress have a gloomy record.

The International Studies drive has to raise $2.5 million by the end of the calendar year, or lose an equal amount which the Ford Foundation pledged if it could be matched. It is known that there is little chance of meeting the deadline.