When the governor convenes the legislature in extra session it shall be done by proclamation, giving to the members such notice as the governor deems necessary of the time of meeting; and when assembled the governor shall inform them of the purposes for which they are convened. The governor shall set apart and proclaim one day in each year as a day of solemn and public thanksgiving to Almighty God for blessings to the people and no business shall be transacted on that day at any of the departments of state. All proclamations of the governor required or authorized by law shall be filed with the secretary of state.