Section 28. There shall be an annual meeting of the stockholders, and the time and place of holding it, and the manner of conducting it, shall be fixed by the by-laws; but it shall be held within ninety days after the end of the fiscal year of the corporation. All meetings of stockholders shall be held in the commonwealth. A written notice, stating the place, day and hour thereof, shall be given by the clerk, at least seven days before the meeting, to each stockholder entitled to vote thereat and to each stockholder who, under the agreement of association or any amendment thereof or under the by-laws, is entitled to such notice, by leaving such notice with him or at his residence or usual place of business, or by mailing it, postage prepaid, and addressed to such stockholder at his address as it appears upon the books of the corporation. Unless the by-laws otherwise provide, a majority in interest of all stock issued and outstanding and entitled to vote shall constitute a quorum. Notices of all meetings of stockholders shall state the purposes for which the meetings are called. No notice of the time, place or purpose of any regular or special meeting of the stockholders shall be required if every stockholder entitled to notice thereof, or his attorney thereunto authorized, by a writing which is filed with the records of the meeting, waives such notice.