When three-fifths of the members elected to the Legislature deem it necessary to call a convention to revise, amend, or change this constitution, they shall recommend to the electors to vote at the next election of members of the Legislature, for or against a convention, and if a majority of the electors voting on the proposition, vote for a convention, the Legislature shall, at its next session provide by law for calling the same; Provided, the votes cast in favor of calling a convention shall not be less than thirty-five per cent of the total votes cast at such election. The convention shall consist of not more than one hundred members, the exact number to be determined by the Legislature, and to be nominated and elected from districts in the manner to be prescribed by the Legislature. Such members shall meet within three months after their election, for the purpose aforesaid. No amendment or change of this constitution, agreed upon by such convention, shall take effect until the same has been submitted to the electors of the state, and adopted by a majority of those voting for and against the same.