“ Appellant applied to the Interstate Commerce Commission under the grandfather clause of the Transportation Act of 1958, § 7 (a) , 72 Stat. 573, 49 U.S.C. § 303 (b) (6) , to transport as a common carrier over irregular routes frozen fruits, berries, and vegetables, and frozen seafoods and poultry when transported with such frozen fruits, berries, and vegetables. The Commission granted a certificate which substantially curtailed appellant's prior operations. ”