In a single stroke, Huntington gained paintings by big-league American artists whose works you could see in major museums across America: Childe Hassam, Robert Henri, Winslow Homer, Edward Hopper, Everett Shinn, Ernest Lawson, Charles Burchfield, Andrew Wyeth, William Glackens.

It was a coup - except for one thing. The obligation to keep Daywood on the walls six months a year kept other works off the walls.

"I don't think of Daywood as a burden," said Margaret Mary Layne, the museum's executive director. The gift arrived at a time when museums in general, and the Huntington museum in particular, "were dying to get things. They weren't thinking that if we do this, it's going to be this way for the next 100 years."

It was the same sort of problem that the Metropolitan Museum of Art took on in 1969 when it accepted the nearly 3,000-piece collection of investment banker Robert Lehman. Lehman had an extraordinary and diverse collection rich in Old Masters paintings, but the terms of the gift called for the museum to add a wing that would display the collection's highlights in a setting that resembled Lehman's New York townhouse.

When the Huntington museum opened in 1952, co-founder Herbert Fitzpatrick gave more than 400 pieces, some by top French artists from the mid-19th to mid-20th centuries: three by landscape painter Charles Daubigny; two by Impressionist Eugene Boudin; a small portrait by Renoir; and a nude portrait in oil crayon by Picasso.

A former CEO of the Chesapeake & Ohio Railway, Fitzpatrick gave American paintings too, including one by Maurice Prendergast, but his collecting impulse was broader than the Daytons' and took him extensively into antique British silver and Middle Eastern prayer rugs. Fitzpatrick gave the museum many of its most treasured works, but Daywood gave a broader collection of American art.

Six months a year is not the worst of restrictions, said Hornor Davis, a former executive director of Sunrise Museum and a former director and member of the acquisitions committee of the Huntington museum.

Consider the Barnes Foundation, whose eccentric donor insisted that the art could never be sold, moved or altered in the way it was displayed. "It had to stay exactly the way it was and where it was when it was given," Davis said. (After a decade of wrangling and legal battles, the Barnes trustees have agreed to move the museum and its extraordinary collection of Impressionist and Post-Impressionist art from suburban Merion, where it was open just three days a week, to a new downtown building near the Philadelphia Museum of Art.)

"Those strings-attached gifts are always a challenge for an institution," Davis said. "Do you question the motives of the donors? It was their passion and they set the rules."

The Daytons had some excellent works by well-known artists and some lesser works by well-known artists, Davis said. "Sometimes they're just small. They wanted it to be a public collection, but it had more of a private-collection feel."

The American Association of Museums tells its members to map out goals for collection-building and proceed with caution, Layne said. "What can we as a community sustain? It's not just 'Can we can conserve it,' but 'Will we have the staff and other resources to make the most of it for the community?'"

The Huntington museum was 13 years old when Mrs. Dayton came calling in 1965, Layne said. It has added some first-rate American and European paintings since then, but most of those gifts have come in ones, twos and threes.

In addition to the Fitzpatrick gift, the museum had at the outset the Herman Dean Firearms Collection. In the 1990s, the museum accepted first the Wilbur Myers glass collection and then the Touma Collection of Near Eastern Art. Each of those collections tie up full time a piece of Layne's exhibit space. So does a small, dedicated gallery that mixes English silver from Fitzpatrick and 200-year-old British portraits from George Bagby.

The museum also has a promised gift from former Blenko Glass designer Winslow Anderson of more than 150 pieces of Haitian art, mostly oil paintings. The Haitian art has already received one big exhibit and will continue to compete for time and space on the walls.

The Daywood conditions do not stipulate the space the exhibit will occupy or how many pieces must be displayed, Layne said. "The idea was that we would become the type of museum that could be worthy of the Daywood Collection."

Former curator Louise Polan used to say that every object has different stories to tell depending on how it is displayed and what it is displayed with, Layne said.

The restrictions are not so onerous as they might appear, said senior curator Jenine Culligan, who was the first to decide to squeeze Daywood exhibits into a much smaller space than the Daywood Gallery. The number of pieces in a Daywood exhibit has not noticeably changed, but they now generally hang salon-style: close together and two or three high.

"I can't imagine this place without Daywood," Culligan said. "The quality of the work overpowers any stipulation they put on the gift."

Daywood exhibits need not be exclusively Daywood, Culligan said. Next year, Culligan will show Daywood alongside "Painting the Beautiful," 25 works by Pennsylvania Impressionists from the Michener Art Museum in Bucks County, Pa. Some of the same artists are in both collections.

Layne said she wants to more fully use the art in her vaults, both by rotating pieces into displays and sending them out on tour more often than now. More than 20 works, including many from the Fitzpatrick gift, went recently to the University of Kentucky Art Museum as part of a larger exhibit that is now up in the Huntington Museum.

"There's a lot of art that could be moving around the country if it's protected," Layne said. "I've never been a hoarder. I never wanted to keep my marbles from everyone else."

Last June, the museum took a big step forward when one staff member and six volunteers finished a five-year project to inventory and digitize the museum's 11,000-piece collection, Layne said. "You don't have to spend two weeks sorting through the collection to determine how many objects you have of a certain thing. If you're considering a show of American paintings between 1910 and 1925, you can pull them all up in a very readable list."

The museum is 55 years old now. Layne has been there 10 years, the past five as executive director. What would go through her mind if someone were to offer another high-quality collection of American art?

"We would look at it through the eyes of how museums are reacting to such offers today," Layne said. "You have to be flexible in how you react to these offers. Something like Daywood, we'd say, 'Yes, yes, yes.' Daywood caused the community to come together to help us build the building and give us the resource we needed to house the collection."