The legislative authority of this state shall be vested in a General Assembly, which shall consist of a Senate and House of Representatives, both dependent on the people. Representatives shall hold office for two years and senators for four years from the day of the general election, except that the speaker of the Senate and the speaker of the House of Representatives each shall hold his office as speaker for two years or until his successor is elected and qualified provided however, that in the first general election after adoption of this amendment senators elected in districts designated by even numbers shall be elected for four years and those elected in districts designated by odd numbers shall be elected for two years. In a county having more than one senatorial district, the districts shall be numbered consecutively.