Be it further enacted, That the city manager, the heads of all departments, and such other officers of the city as may be designated by vote of the council, shall be entitled to seats in the council, but shall have no vote therein. The city manager shall have the right to take part in the discussion of all matters coming before the council, and the directors and other officers shall be entitled to take part in all discussions of the council relating to their respective offices, departments or agencies.