Cook soup and marrow bones in 8 cups boiling salted water in heavy kettle until meat falls from bones.
Remove fat from meat; discard bones.
Boil liver and heart in stock until tender; remove, reserving 6 cups stock.
Process meat through food grinder; return to stock.
Stir cornmeal and flour into reserved stock gradually; add seasonings.
Cook over low heat for 1 hour, stirring frequently.
Pour into bread pans; chill until set.
Wrap in waxed paper; store in refrigerator.
Slice as needed; fry in lightly greased skillet.