“ The principle that one who has been unjustly enriched at the expense of another may be made to respond to the latter was without application, for here the shipper was responsible in no greater degree for what occurred than was the carrier. ”

“ In our judgment, it is wholly improper, in the absence of clear allegations of the rendition of services under a distinct protest, for a court to find that a shipper had, in effect, undertaken conditionally to pay according to a rate different from that published in compliance with the statute.'
2. The injunction, in obedience to which the schedule was put into effect and maintained during the period covered by the shipments, was awarded without taking any bond or imposing any terms or conditions for the security of the carrier ”

“ When this right was exercised the carriers did not ask a suspension of the injunctions pending a hearing and decision, and the injunctions remained in force until the cases were dismissed. Neither at the time of the dismissal nor at any prior stage of the proceedings was there any order saving or securing to the carriers a right to demand or collect additional compensation in respect of shipments whereon the schedule rate was demanded and paid while the injunctions were effective. ”