In and for each district heretofore or hereafter created pursuant to this chapter or pursuant to a special act of the General Assembly, a commission is hereby created as a body corporate, invested with the rights, powers and authority and charged with the duties set forth in this chapter. The commission shall be known by the name of the district, except that the word “commission” shall be substituted for the word “district.” Except as a special act creating the district shall otherwise provide, the commission shall consist of seven members, residents of the district, appointed by the State Health Commissioner, in the manner hereinafter provided, who shall notify each governing body immediately after such appointments. Representation on the commission shall be apportioned among the political segments of the district on a population basis so far as it may be practical to do so; but each political segment, however, shall be entitled to at least one representative on the commission; and all appointments thereto shall be made by the State Health Commissioner from a list of not less than one nor more than five names furnished to him by the respective governing bodies of each political segment of the district. Except as a special act creating the district shall otherwise provide, in making the original appointments, one of the members shall be appointed for a term of one year, two for a term of two years, two for a term of three years, and two for terms of four years each; subsequent appointments shall be made for a term of four years, except appointments to fill vacancies which shall be for the unexpired terms. Members of the commission shall hold office until their successors have been duly appointed and qualified.