In addition to the examinations made and conducted by the Comptroller of the Currency, every Federal reserve bank may, with the approval of the Federal reserve agent or the Board of Governors of the Federal Reserve System, provide for special examination of member banks within its district. The expense of such examinations may, in the discretion of the Board of Governors of the Federal Reserve System, be assessed against the banks examined, and, when so assessed, shall be paid by the banks examined. Such examinations shall be so conducted as to inform the Federal reserve bank of the condition of its member banks and of the lines of credit which are being extended by them. Every Federal reserve bank shall at all times furnish to the Board of Governors of the Federal Reserve System such information as may be demanded concerning the condition of any member bank within the district of the said Federal reserve bank.