Introduction, 604. — Circumstances under which motor-carrier regulation has developed, 606. — Characteristics which explain the regulation of railroads and other utilities largely absent, 608. — Restriction of entrance must be distinguished from other phases of regulation, 613. — Such restriction only partially explained by the nature of the industry, 615. — Protection of railway interests the dominant consideration, 620. — Delicate problems involved in granting of certificates of convenience and necessity, 625. — Difficulties and dangers of regulation exemplified by motor freight regulation, 632. — The theory of special highway use improperly reflected in motor-carrier regulation and taxation, 639. — Conclusion, 646.