“ Whether a suit arises under a law of the United States must appear from the plaintiff's pleading, not the defenses which may be interposed to, or be anticipated by it. Petitioner's pleading, which we have summarized, satisfies this requirement since it adequately discloses a present controversy dependent for its outcome upon the construction of a federal statute. ”

“ Further, the initial carrier is made liable to the shipper for full damages sustained, notwithstanding any limitation of liability in the receipt or bill of lading, with the exception, important here, that where a carrier by authority or direction of the Interstate Commerce Commission maintains rates dependent upon the value of the property declared in writing by the shipper, such declaration also limits liability of the carrier for loss or damage to an amount not in excess of the declared value. ”

“ The carrier is made liable to the holder 'for any loss, damage, or injury to such property caused by it' or connecting carriers. If the injury does not occur on the initial carrier's line, but it responds in damages, it is entitled to recover over from the responsible carrier. ”