Dissolve yeast in warm water. Add eggs, sugar, oil, and salt and beat together. Add soy flour and 2 cups white flour, beating thoroughly. Add dry milk and remaining 2 cups white flour, beating thoroughly. Mix in wheat germ and whole-wheat flour. Knead 10 minutes by hand or 5 minutes with electric mixer and dough hook. Put in well-oiled bowl, turning to coat dough. Cover with plastic wrap and let rise in warm place until double. Punch down and form into 3 loaves. Put in greased 8-½x4-½x2-⅝-inch loaf pans. Grease tops of loaves, cover, and let rise until double. Place in cold oven and turn heat to 400 degrees F. After 15 minutes, reduce heat to 375 degrees F and bake 20 minutes more. Remove from oven and immediately remove loaves from pans. Brush crusts with butter and place loaves on racks to cool.