Clean, scrape and wash thoroughly the pig's knuckles. Combine with the sauerkraut and cover with cold water. Cook slowly until the knuckles are tender. To the beaten egg, add the melted butter and water. Sift the flour, salt and nutmeg together and combine with egg mixture. Beat thoroughly. If necessary, add more flour to make batter stiff enough to drop from spoon. 20 minutes before serving drop the batter by spoonfuls into the hot sauerkraut. Cover pot tightly and serve as soon as dumplings are cooked.