Section 46. A stockholder in any corporation which shall have duly voted to sell, lease or exchange all its property and assets or to change the nature of its business in accordance with section forty-two, who, at the meeting of stockholders, has voted against such action may, within thirty days after the date of said meeting, make a written demand upon the corporation for payment for his stock. If the corporation and the stockholder cannot agree upon the value of the stock at the date of such sale, lease, exchange or change, such value shall be ascertained by three disinterested persons, one of whom shall be named by the stockholder, another by the corporation and the third by the two thus chosen. The finding of the appraisers shall be final, and if their award is not paid by the corporation within thirty days after it is made, it may be recovered in contract by the stockholder from the corporation. Upon payment by the corporation to the stockholder of the agreed or awarded price of his stock, the stockholder shall forthwith transfer and assign the stock certificates held by him at, and in accordance with, the request of the corporation. The word ''sell'' as used in this section shall not include mortgage or pledge.