Divide off one softball-size portion of white dough, and set aside.
Divide off two softball-size portions of wheat dough.
Roll out one whole wheat portion into a large rectangle.
Sprinkle with caraway and anise seeds, and roll back up into a ball.
Cut off two thirds of each softball size portion, and roll into a rope 18 inches in length.
Loosely braid on a well greased baking sheet.
Sprinkle with sesame seeds.
Make an 18 inch rope from each remaining one third portion.
Braid loosely, and center on top of the first braid.
Combine 1 egg yolk and 1 tablespoon water, and brush bread.
Sprinkle generously with sesame seeds or poppy seeds.
Let rise until double.
Bake in a 400°F.oven for 10 minutes, and then reduce heat to 350°F. and bake an additional 30 minutes.