Cook 1/4 cup chopped celery, 1/4 cup chopped onion, and 1 bay leaf in 2 tablespoons butter till tender.
Discard bay leaf.
Add 3 cups dry bread cubes and 1 tablespoon snipped parsley; mix.
Drain 1/2 pint shucked oysters, reserving liquid; chop oysters.
To bread mixture add oysters; 1 beaten egg; 1/2 teaspoon salt; 1/4 tea spoon dried rosemary leaves, crushed; and dash pepper.
Add milk to oyster liquid to make 3 tablespoons; add enough to stuffing to moisten.
Plunge four 11/2-pound live lobsters head first into enough boiling, salted water to cover.
Cook 2 minutes.
Remove from pan; place lobsters on backs on cutting board.
Cut in half lengthwise: draw sharp knife from head down to base of abdomen.
Discard all organs in body section except brownish green liver and red coral roe.
Remove black vein.
Crack large claws and spread body open.
Fill each lobster cavity with stuffing.
Place, shell side down, on baking sheet.
Baste with 1/4 cup melted butter.
Bake at 350° for 30 to 35 minutes; brush with butter once or twice during baking.