“ The statute here considered we think plainly imposes a burden upon the carrier of interstate commerce, and is not an aid to it, but, in its direct and immediate effect, it is quite the contrary.
The power to regulate the relative rights and duties of all persons and corporations within the limits of the state cannot extend so far as to thereby regulate interstate commerce. The police power of the state does not give it the right to violate any provision of the Federal Constitution. ”

“ This is certainly a direct burden upon interstate commerce, for it affects most vitally the law in relation to that commerce, and prevents the exemption provided by a legal contract between the parties from taking effect except upon terms which we hold to be a regulation of interstate commerce. ”

“ The railroad company receiving the freight from the shipper has no means of compelling the servants of any connecting carrier to answer any question in regard to the shipment, or to acknowledge its receipt by such carrier, or to state its condition when received. ”