Every incorporated express company doing business in this State shall keep a general office in this State at some place on the line of its transportation, in which it shall keep its charter, books, papers, accounts and contracts, or copies thereof, showing the value of its property of all kinds, its receipts and disbursements on account of business done in this State, and its indebtedness. It shall make a full annual statement of all such matters as shown by its books to the Railroad Commission of Texas, and such additional statements as may be required by such Commission, which statements shall be certified to be correct and sworn to by the president and secretary, or general manager in Texas of such company. Such company shall permit any member of the Railroad Commission of Texas or its authorized agent to examine at any time, any and all books, papers and contracts in its said office.