Whenever it shall appear to the governor that the welfare of the state or any section thereof, or the welfare and security of banks and other institutions under the supervision of the bank commissioner, hereinafter referred to as banks, or their depositors or shareholders so require, he may proclaim that a banking emergency exists and that any bank or banks shall be subject to special regulation as hereinafter provided until the governor, by proclamation, declares the period of such banking emergency terminated. The governor may likewise declare such legal bank holidays as in his judgment such an emergency may require.