In recent years the development of manufacturing industries in Saxony and the resultant pollution of the water has greatly reduced the abundance of the mollusks and consequently the output has been much restricted. The average annual yield in the twenty years ending in 1879 was 163 pearls; in the twenty years ending in 1899 it was 66 pearls, and in the six years ending in 1905 the annual average was 58 pearls. Owing to high water, there was no fishing in 1888; and with a view to permitting the resources to recuperate, the fishery was suspended from 1896 to 1899, inclusive. Omitting these five years, the average yield during each season in the two decades ending 1899 was 88 pearls. At the end of each season, the pearls secured are turned over to the director of forestry for the district of Auerbach; by him they were formerly sent to the royal cabinet of natural history, or to the royal collection at Dresden, but since 1830 they have been sent to the royal minister of finance, by whom they are sold each year. The total proceeds from these sales now amount to about 55,000 marks. In former times, according to Dr. Nitsche, it was customary to use these pearls in making royal ornaments. This was the origin of the famous Elster necklace, consisting of 177 pearls, now in the art collection in the Grüne Gewölbe in the palace at Dresden. Another assortment in that collection consists of nine choice, well-matched pearls, weighing 140 grains. For a necklace of Saxon pearls, the property of a duchess of Sachsen-Zeitz, the sum of 40,000 thalers ($28,400) is said to have been refused. In Prussian Silesia the pearl-mussel is found in the upper tributaries of the Oder, especially in Bober River from Löwenberg to the sources among the foot-hills of the beautiful Riesengebirge, in the Lusatian Neisse to Görlitz, the Queiss above Marklissa, and in the Juppel as far as Weidenau. The Queiss has been famous for its pearls since the sixteenth century, and even yet specimens of great beauty are obtained therefrom. As long ago as 1690, Ledel complained of the diminution of the number of mollusks owing to their wilful destruction by children; and in 1729 the government issued a rescript in Upper Lusatia (_Oberlausitz_) recommending the care of the young mollusks.[214] Pearls are also found in the White Main a short distance from its source, in the head waters of the Saale, and in numerous other mountain-draining streams of middle Germany. Indeed, references could be made to the discovery of pearls in nearly every stream of Germany at some time during the last three or four centuries.