Section 51. If a railroad corporation, having executed a mortgage of its property, rights and privileges, or of a part thereof, to trustees for the benefit of its general creditors, or of a particular class of creditors, makes default in the performance of the condition of the mortgage, so that the trustees or their successors are entitled to the actual possession and usufruct of the property, rights and privileges therein conveyed, in trust for the purposes specified in the mortgage, the trustees, after entry, instead of retaining actual possession of the mortgaged premises and operating the railroad, may contract with the corporation or other competent party to take or retain for them the possession of the mortgaged premises, and to use and operate the same on its own responsibility, accounting with the trustees for the earnings and income, and paying over the profits and net income periodically, when and as far as necessary for the performance of the conditions of the mortgage, if a majority in interest of the bondholders or creditors under the mortgage shall so vote, in person or by proxy, at a meeting called therefor, notice of which shall be published ten days before said meeting in two or more daily newspapers published in Boston, and in at least one newspaper published in each county where the railroad is located. All liabilities incurred by the corporation or other party in operating the railroad under such contract shall be held as claims against and be paid out of the income, in the same manner and to the same extent as if the property had remained in the actual possession of the trustees and been operated by them.