In a large mixing bowl, dissolve yeast in warm water; let stand for 5 minutes.
Add the shortening, eggs, sugar, salt and whole-wheat flour and beat until
smooth. Add enough all-purpose flour to form a soft dough.
Turn onto a floured surface and knead until smooth and elastic, about 6-8
minutes. Place in a greased bowl, turning once to grease top. Cover and let rise
in a warm place until doubled, about 1 hour.
Punch dough down. Divide into 4 portions; shape each portion into 12 balls.
Place 1 inch apart on greased baking sheets. Cover and let rise until doubled,
about 25 minutes. Bake at 375°F. for 11-15 minutes or until browned. Brush with
butter.