Additional Harvard land will come under the control of the Cambridge Historical Commission if a proposed plan to consolidate Cambridge's four existing historic districts into a single operational unit passes the State House this summer.

"The Old Cambridge Historic District," which would include land along the 17th century "Watertown Path," would bring Austin Hall and part of the Old Yard under commission supervision.

Donald C. Moulton, assistant vice president for community affairs, said yesterday that the proposed plan, devised under the provisions of the Massachusetts Historic District Act of 1971, was a cooperative effort between the commission, the University, and members of the Cambridge community.

Moulton, who represented the University viewpoint to the commission, said relations between Harvard and the commission have been good in the past. "I don't think our objectives will conflict in any way in the future," he added.

Charles Sullivan, chairman of the commission, said yesterday that University property currently under commission supervision includes seven buildings in the Square Area, part of the Old Yard and land at the Law School and at Radcliffe.

Any plans to alter the exteriors of buildings or start construction on land in historic district must be approved by the commission.