Wash thoroughly, clearing the ventricles of all coagulated blood, and stuff with a good force-meat of crumbs, minced pork, onion, parsley, and other seasoning. Fill all the orifices with this, packing it in well; sew the heart up in mosquito-netting fitted to the shape, and boil two hours in weak stock, which, by the way, you may use again for soup. Let the heart get almost cold before taking it out, put a weight upon it, and do not undo the cloth until the heart is cold, stiff, and flattened. Cut perpendicularly into thin slices. Cook calf's heart in the same way.