§ 61. Directors from districts. The by-laws may provide for the use of one or more of the following: (a) that the territory in which the corporation has members shall be divided into designated districts, and that directors shall be nominated or elected therefrom in a designated number and manner, either by the members therein or by district delegates elected by such members or by the membership at large; (b) that primary nominations or elections shall be held in each district to nominate the directors apportioned to such districts and that the result of all such primary elections may be ratified by the next regular meeting of the corporation or may be considered final as to the corporation; (c) that, in the case of a corporation having local associations, incorporated or otherwise, affiliated with it or a member of it, election of a designated number of directors may be by the members of such local association at a meeting thereof, followed by transmission of the ballots and of a certified canvass thereof to the annual meeting of the corporation; (d) that one or more directors may be appointed by any public official or commission or by the other directors. Directors so appointed shall represent primarily the interest of the general public in such corporation; need not be members of the corporation; and shall not constitute more than one-fifth of the entire number of directors.