Senators and members of the Assembly shall be duly qualified electors in the respective counties and districts which they represent, and the number of Senators shall not be less than one-third nor more than one-half of that of the members of the Assembly.

It shall be the mandatory duty of the Legislature at its first session after the taking of the decennial census of the United States in the year 1950, and after each subsequent decennial census, to fix by law the number of Senators and Assemblymen, and apportion them among the several counties of the State, or among legislative districts which may be established by law, according to the number of inhabitants in them, respectively.