The course of art does not run smooth. It is full of nodes and clumps.

Certain cities more than others--Philadelphia more than Baltimore, Paris more than Marseilles--have lured the artists' muse. So have certain country villages--Provincetown and Taos--and even certain bars--the Moulin Rouge in Paris, Els Quatre Gats in Barcelona, the Michelangelo in Florence, the Cedar in New York.

One such congelation, previously unstudied, is the subject of "Americans in Brittany and Normandy: 1860-1910," a fascinating touring show, arranged by scholar David Sellin, that is now at the National Museum of American Art.

It stars a pair of small hotels, the Voyageurs in Pont-Aven and the Baudy (called the Bawdy) in nearby Giverny. And it has a cast of hundreds. If both towns sound familiar, it is, of course, because Claude Monet built his garden around a pond in Giverny and Paul Gauguin changed history while in Pont-Aven.

But those two French immortals play only minor roles in Sellin's exhibition, which focuses instead on those painters from America who somehow got there first.

Artists from America were gathering in Pont-Aven, and painting there together, at least 20 years before Gauguin arrived. The first Americans in Giverny had never heard of Monet (though one of them, Theodore Butler, would marry Monet's stepdaughter).

At first they were a handful of gentlemen bohemians, bearded and collegial, who, while searching for the picturesque, the beautiful, the rugged--and, of course, the cheap--had found northwestern France. They later came in droves. In time there were so many Americans around that baseball games were organized by rival artists' camps.

Nearly 700 guests signed the Baudy's register between 1887 and 1899. Of these the vast majority were painters from the United States.

By then the care and feeding of visiting Americans had become the major local cottage industry. "Often in my walks, while following the course of the river, I would come upon a number of girls and women engaged in cleansing the family linen, and also that of the artists. They discussed the relative merits of their patrons, one declaring that 'her monsieur' could paint the best pictures in town, whereon would ensue a war of words until one would think he was in bedlam," wrote Anne C. Goater in 1885.

Brushes, paints and canvas were sold in the hotels. The river banks and coastal dunes were dotted every summer day with artists' white umbrellas. "So usual a sight was the painter at work," wrote one artist, "that his arch enemy, the small boy, no longer thought to stop and watch."

Many of these artists have long been forgotten. But others are still famous. A surprisingly large number of our nation's best-known painters play parts large or small in Sellin's superb catalogue and in his lovely show.

They include: James Abbott McNeill Whistler (who spent three months in Brittany in 1861 and returned to Normandy in 1865 to paint seascapes in the company of Courbet and Monet); John Singer Sargent (who thrice worked in Brittany, and painted "Madame X" there), Winslow Homer, George Inness, Childe Hassam, William Morris Hunt, Elihu Vedder, Charles Adams Platt (the architect who designed the Freer Gallery), Robert Henri, Cecilia Beaux, Theodore Robinson, J. Alden Weir, Thomas Dewing, Arthur Wesley Dow, John Henry Twachtman, Maurice Prendergast, Washington's Augustus Tack, the black painter Henry O. Tanner, the muralist Kenyon Cox, the sculptors Frederick MacMonnies and Alexander Stirling Calder, and Philadelphia's Stephen Parrish, who brought his painter son, Maxfield, along.

Mary Cassatt is not represented, though while visiting the Baudy in 1894 she drank whiskeys there with Ce'zanne. Nor is Thomas Eakins, who chose to stay in Paris, though large numbers of his students and many of his friends are included in the show.

There are 118 pictures on display. Most of them portray pious peasants in white bonnets, the sails of the fishing fleets or landscapes in soft sunlight, but they share no single style and they do not form a school. Yet many of these paintings serve to bridge the gap between the brown, cow-dotted landscapes of older Barbizon School painting and the high-keyed flickerings of the Impressionists.

Paris, not the countryside, brought these Americans to France. Most had come to study in the city's ateliers, and to paint the polished pictures that, with luck, might win exhibitions in the annual Salon. The Salon was held in spring, and no sooner had the last medal been awarded than the exodus began.

"Paris was hot and impossible in its whiteness," wrote one of the Americans. "Good resolutions of remaining at the Beaux-Arts till the last day of the session faded gradually away. The cafe's on the Boulevard began to pall . . . and familiar faces on the street became more and more rare. It was time to go to the country."

Brittany and Normandy were convenient--and exotic. To Philadelphia's Robert Wylie and his small band of colleagues who "discovered" Pont-Aven in 1866, that little town in Brittany seemed to be a remnant of another, older world. It was a land of poor soil, extreme poverty, intense piety and residual paganism. To the visiting Americans, the people of the Breton coast--the men in their broad hats, the women in their huge, stiff coifs--seemed almost medieval. Brittany, in short, offered perfect subjects for the art of the Salon.

"It is still in Brittany," wrote Gauguin to his wife in 1885, "that one lives the cheapest." Life had been still cheaper when Hunt and Vedder painted there in 1866. "We found or made a large studio on the ground floor of an old house," wrote Vedder. "It was literally the ground floor, for the floor was the ground, and Hunt delighted in it. You could make holes and pour in the dirty turpentine and fill them up again . . ." At the Voyageurs in Pont-Aven, room and board, excluding tobacco, wine and candles, cost $10 per month.

Most of the Americans, at least those in the first waves, preferred straightforward realism. They painted what they saw. In 1875, before he had turned 20, Sargent painted fresh-caught octopuses wriggling upon the deck of a Breton fishing smack. The women who appear in his "Oyster Gatherers at Cancale" (1878), a superb work on loan from the Corcoran's collection, wear heavy wooden shoes.

Whistler chose to paint the sea, Inness picked the rocky coast, Hunt the local farmers. Early on in Pont-Aven, most of the Americans would make their studies out of doors and then work up their paintings in the Chateau de Lezaven, "an old building, just out of the village, half farmhouse, half chateau," in which Wylie and his friends kept their easels and their props.

Gauguin would work there later, while bitterly complaining of academic hacks working all around.

The Americans in town might have looked like gypsies--"Brown men with long beards have a lonely look even when they go in bands," wrote one of their company--but their art was never radical. The first Americans in Giverny had never heard of Monet, and probably would have sneered at his innovative art. They picked the place, by chance, in 1887, from the window of a train. "Fellows, just look at that--isn't it lovely," said painter Willard Metcalf to his traveling companions. They looked, and they agreed. Only later did they learn that the place they had selected was the town of Giverny.

The Americans in Pont-Aven were as adventurous in life, and as conservative in taste. One of them, J. Alden Weir, experienced with displeasure his first Impressionist exhibit in 1877. "I never in my life saw more horrible things," he wrote. "It was worse than the Chamber of Horrors. I was there about a quarter of an hour and left with a headache, but I told the man exactly what I thought." By 1895, Weir would be viewed as an Impressionist. The way Monet's teachings would be absorbed by his neighbors--a development made clear by Theodore Robinson's sweet picture of the Butler wedding--is a subtheme of the show.

The Americans of the region thought themselves quite daring, but by Paris standards were not really so. Mrs. Frederick MacMonnies, for example, thought it "quite absurd" that Isadora Duncan, who had leased a house nearby, rose early every morning to dance nude on dewy grass. And in 1900, Mrs. William Dodge dismissed her husband's model "for answering a knock on the garden gate naked, to find not an artist neighbor, but a stunned small town Presbyterian minister from Virginia clasping a letter of introduction from the artist's maiden aunt."

Sellin's show is fine. It takes pictures we know well, for instance the Corcoran's "The Road to Concarneau" by William Lamb Picknell, and puts them into context. And it rescues from oblivion highly worthy artists, for instance Dennis Miller Bunker, who deserve fame. While other exhibitions here have dealt with Americans in Dusseldorf and London and Italy, this one clarifies the debt that our 19th-century painters owe to rural France.

A few settled down there. But hundreds more returned, and in doing so helped pave the way for America's acceptance of the new in art.

To fully appreciate Sellin's show, one ought to read his catalogue. It is a first-rate work. The exhibit, which was organized by the Phoenix Art Museum, closes Aug. 14.