BLUEBERRY BANANA PIE

4 cups fresh blueberries    1 teaspoon lemon juice
1 cup sugar                        2 ripe bananas
3 Tablespoons flour            9-inch graham cracker 
pie Shell

Mix sugar, flour, lemon juice and 1 cup  berries.  Cook over medium heat until thick.  Cool:  Add three cups uncooked berries:  Line bottom of crust with sliced bananas:  Add blueberry mixture:  Serve with whipped topping: