In what one National Gallery of Art curator called a "blockbuster" multimillion-dollar acquisition, the gallery yesterday announced gifts of nine famous paintings, including E'douard Manet's "Ball at the Opera," an Henri Rousseau jungle picture and important works by American artists James Abbott McNeill Whistler, Edward Hopper, Thomas Eakins and George Bellows.

"Cape Cod Evening," a moody picture of introspective, isolated figures, is the gallery's first work by Hopper, a major 20th-century American realist. The gifts also include another first, "Coast Near Antibes," by French Neo-Impressionist Henri-Edmond Cross, and two colorful works by Andre' Derain that will help remedy what has been the gallery's lack of important work from the French Fauve period.

"This is a quantum leap in the gallery's French and American collections happening at one spectacular moment," said John Wilmerding, the gallery's curator of American art. "Curators and directors work all their lives for this kind of gift."

Eight of the paintings were once part of the private collection of the late publisher John Hay Whitney, a trustee of the gallery from 1961 to 1979, and were given through a trust set up during his lifetime to administer the distribution of part of his estate. From the same trust yesterday came a $2 million cash gift to the gallery's permanent fund for future acquisitions, which seeks to raise $50 million for a permanent endowment.

The Manet is a bequest of the late Doris Havemeyer, who inherited the painting from her mother-in-law, Louisine Havemeyer, one of the great American collectors of modern French art.

National Gallery officials yesterday declined to put a dollar value on the gifts, but one source in the art world said the Whitney estate had been offered--and had refused -- $2 million for just one of the paintings given yesterday.

"Obviously, it's a very valuable gift in every sense of the word," Wilmerding said. "I don't know how to put a price on it. These kinds of things simply don't come on the market."

"These are marvelous pictures," said National Gallery Director J. Carter Brown. "John Hay Whitney had a great gift as a collector, a marvelous eye. He's given us a wonderful Christmas." Brown also said he was grateful to Whitney's widow, Betsey Cushing Whitney, who, he said, "had control over the disposition of these pictures."

The Manet, dated 1873, is currently on view in the gallery's special exhibition, "Manet and Modern Paris." Showing the interior of the old opera house in Paris, where lower-class women in masks are meeting with upper-class men, the painting reflects Manet's concern for social problems of the time, his bold effort to look directly at problems in the modern, bustling metropolis.

Brown said yesterday he was especially happy about the Derain and Cross paintings. "We're weak in the Fauve area and this [the two Derains] will beef that up," he said. He added that "for some reason, although we have fabulous things from the 19th century, we never had a Cross."

The early 20th-century Fauve movement, so called because a critic considered Derain, Matisse and others in it so outrageous and unconventional that they could be only "wild beasts," was one of the first great experimentations by artists with the intense and even distorted use of colors in landscapes to express personal emotions, according to Wilmerding. The two 1905 Derains, "Charing Cross Bridge, London" and "Mountains of Collioure," both show, in different landscapes, the use of color at its most intense.

Wilmerding said that while the gallery had several later paintings by Derain, none were from his Fauve period.

The Cross painting (1891-92) is one of his most brilliant examples of "pointillism," so called because of the countless brilliant dots, rather than brush strokes, that make up the picture. Wilmerding said the picture of a coast is "typical of a whole group experimenting with broken brushwork for decorative purposes, an early interest in abstract color."

The painting by Rousseau, the great modern French primitive, is "Tropical Forest With Monkeys"--a very large, exotic scene dated 1910, the year he died. Rousseau painted it by working almost entirely out of his imagination and from examples of quite tame monkeys that he saw in the Paris zoo.

"This is quite wonderful, a witty picture full of monkeys in a forest," said Wilmerding. He said the "crazy kind of witticism" in the picture comes from Rousseau's having essentially "turned the city park into a wild jungle. This is a childlike work of fantasy crossed with exotic imagery of a distant country."

The Whistler painting, "Wapping on Thames," (1861) adds to the National Gallery's existing strength, as it already has several notable Whistlers, including "The White Girl." Whistler's mistress, Joanna Heffernan, was the model for both paintings, appearing in the newly acquired work as a young woman seated with others at a table against a busy harbor background. The bearded man beside her in "Wapping on Thames" is French artist Alphonse Legros.

The newly acquired painting is an early one by Whistler, one of America's most famous 19th-century artists, but who was equally at home in England and France. Said Wilmerding: "He worked on it just as he established himself in Paris, just as he was looking at contemporary French art, the most avant-garde modern art in Paris at that time. It has the feeling of Courbet and Manet about it."

The Bellows painting, "Club Night" (1907), is a powerful boxing scene, the first of six that the artist did on that theme. It has been on view in the National Gallery's exhibition of Bellows' boxing pictures, which closes this weekend.

Bellows was among the key painters in the "Ash Can" school, whose practitioners depicted modern city life in New York at the turn of the century. Their paintings had, Wilmerding said, "the crowd, the excitement of immigrants in the new world, the dynamism of a new century," and they were roundly criticized for what was considered vulgar subject matter. At that time, boxing was illegal in New York and took place in back rooms.

"Hopper would surely be in contention for America's major realist painter of the 20th century," said Wilmerding. "Cape Cod Evening," dated 1939, is typical of Hopper's best work. The artist spent much time on the Cape, where he most often painted lighthouses and old Victorian homes under varying light conditions. According to the artist himself, the painting's setting is "no exact transcription of a place, but pieced together from sketches and mental impressions of things in the vicinity."

Eakins' "Baby at Play," dated 1876, conveys an extraordinary and powerful sense of reality, although its subject, a baby playing with blocks, is simple. "The painting has this effect of largeness and mystery," said Wilmerding. "In the size of the child you have this feeling of introspection which is almost inconsistent with childhood. The artist has given an intimate sense to what would seem to be a superficially ordinary subject."

Wilmerding said Eakins is known mainly for his portraits of people preoccupied at work or leisure, "so they become studies of the human condition."

The Bellows and Manet are already on display. Wilmerding said the Eakins was going up yesterday, and that the Rousseau would go up in the next week or so. "Some of the paintings need light cleaning," he said. "They all will be put up in due course over the next few months."