In a 1-quart glass measuring cup or bowl, combine cornmeal, oats, bran and wheat germ. Pour in 2 cups boiling water. Stir thoroughly. Set aside to cool. Place yeast in large mixing bowl. Add 1/2 cup warm water. Stir to dissolve yeast. Add agave, butter and salt. Mix thoroughly. Add cooled cornmeal mixture. Stir until smooth. Stir in whole wheat flour. Gradually add unbleached flour, one cup at a time, until mixture is stiff enough to knead (about 2 1/2 cups). Sprinkle remaining flour on board. Knead dough for 10 to 12 minutes until smooth. Add additional flour as necessary. Shape dough into ball. Lightly grease clean mixing bowl. Place dough in warm, draft-free place until doubled in size (about 1 1/2 hours). Punch down dough to remove air bubbles. Turn out onto lightly floured board. Divide dough in half. Shape each half into a round loaf. Place loaves on a large lightly greased cookie sheet or 2 pie plates. Cover. Place in warm, draft-free place until double in size (about 1 hour). Bake in preheated oven at 350°F for 40 to 50 minutes or until bread sounds hollow when tapped. Remove loaves from cookie sheet. Cool on wire racks.