Seligman developed a strong interest in modern art for the New York gallery, dealing in works by Pierre Bonnard, Paul Cézanne, Honoré Daumier, Edgar Degas, Henri Rousseau, and Vincent van Gogh but in the face of resistance from other members of the family turned to César Mange de Hauke who had studied art in England and France and arrived in the United States in 1926. For a short period de Hauke worked as a sales representative for Seligman but the two soon decided to set up a subsidiary, de Hauke &amp; Co., Inc., to deal in modern art. Established in 1926, the company purchased art in Paris and London for sales in the United States. Works by Amedeo Modigliani, Odilon Redon, Ker-Xavier Roussel and Édouard Vuillard were exhibited and sold in New York. Soon coverage was extended to Paul Cézanne, Jacques-Louis David, Eugène Delacroix, Jean Ingres, Pierre-Auguste Renoir, and Georges Seurat. Pablo Picasso was featured twice, first in 1936 with paintings from the Blue Period and the Rose Period, and second in the November 1937 exhibition "Twenty Years in the Evolution of Picasso" showcasing the painting "Les Demoiselles d'Avignon" which Seligman had acquired from the Jacques Doucet estate. The Museum of Modern Art acquired the painting for $24,000 raising $18,000 toward the purchase price by selling a Degas painting and obtaining the remainder from donations by the co-owners of the gallery Germain Seligman and Cesar de Hauke. As a result of the successful new business strategy, the other family members withdrew their opposition and Jacques Seligmann &amp; Co., Inc. adopted Seligman's evolving preferences. De Hauke's company was dissolved and de Hauke returned to Paris. Seligman was a member of committee coordinating art for the New York World Fair in 1939.