The Boston bomb squad and other law enforcement agencies were called to the Bryant Street home of Dean of the Faculty Jeremy R. Knowles Monday night to investigate a package received in the mail by the dean and his wife.

Harvard, Cambridge, Boston and state police, as well as the Cambridge fire department and Cambridge and Boston bomb experts, were at the scene, and the Knowles evacuated their home.

"We blocked off a couple of side streets there," said Det. Frank Pasquarello of the Cambridge police department. "We had the package x-rayed, and it turned out to just be something from friends."

The package, which Knowles described as a "brown bookbag with no return address," was found to be a harmless gift from a friend. The package was suspicious, law enforcement officials said, because it was addressed to "Mr. and Mrs. Knowles" instead of "Professor" or Dean" and because it lacked a return address.

"I had faxed 42 departments the previous week to be cautious [about the mail]," Knowles said yesterday. "Was I not to follow my own stricture?"

The scare at the Knowles home follows mail bomb attacks on prominent scientists at the University of California at San Francisco and Yale University last week. The California scientist, Charles Epstein, lost several fingers last Tuesday after opening a package at his home.

Knowles is a noted expert in enzymes and in the boundary between chemistry and biochemistry. Harvard police and the FBI are waging an informational campaign to make people aware of the mail bomb threat.

Knowles said a steady stream of law enforcement officials entered the house and called the package ominous-looking.

"The bomb squad expert came out of the house and said, 'this has all the makings of a real one,'" Knowles said.

The dean said he went out to supper in his bedroom slippers while experts tested the package.

Officer-in-charge Lawrence J. Murphy and Lt. John F. Rooney of the Harvard police department emphasized again yesterday that it is important for all University students, faculty, staff and affiliates to be cautious when handling mail.

Other signs of a possible mail bomb include excessive postage, oily stains or discolorations and protruding wires or tinfoil