§ 235. Quorum; term of office; removal; vacancies in board of commissioners. A majority of the members of any board of commissioners appointed under this article shall be a quorum for the transaction of any business or the performance of any duty or function, or the exercise of any power, conferred or enjoined upon them. Any commissioner may be removed for cause at any time by the power appointing him, but no commissioner shall be removed without due notice and an opportunity to be heard in defense; and no commissioner thus removed is or shall be eligible to be again appointed to the office of commissioner. In case of the death, resignation or removal from office of any commissioner the vacancy shall be filled by the power appointing him, within thirty days after such removal, or within thirty days after notice in writing to such appointing power given by some member of the board, or by the corporation hereinafter mentioned, of such death or resignation, and a certificate of every such appointment shall be filed as hereinbefore required. Except as otherwise provided by law, the terms of office of the commissioners shall determine and expire with the performance of their functions as hereinabove prescribed.