Preheat oven to 325° Fahrenheit. Grease 1 large or 2 small loaf pans. In a large bowl, cream butter and sugar. Add bananas and eggs. Pour milk into a small bowl and stir in soda; stir into banana mixture. Blend in marmalade. Gradually add flour and salt. Stir in nuts, then pour mixture into pan(s). Bake about 1 hr., or until a knife inserted into center comes out clean. Cool in pan. Makes 1 large loaf or 2 small loaves.