Dissolve yeast in cooled milk. Mix with 1 tablespoon of sugar and ½ cup flour. Beat until well blended. Let rise in warm place until double in bulk, about half hour. Cream butter and sugar, add eggs beaten with salt, lemon rind, mace and remaining flour. Add yeast mixture and beat well, about 10 minutes with electric mixer. Butter tube pan, sprinkle with bread crumbs. Pour in batter and let rise until triple in bulk, about 1 ½ hours. Bake 40 minutes in 350° oven. Remove from pan and pour Rum Sauce over top and sides.