11.  In any part of the service in which substitutes are employed certifications of those eligible to original appointment shall be made for filling vacancies in substitute positions only, and vacancies in regular positions shall be filled by the appointment or promotion thereto of substitutes in the order of their original appointment as substitutes whenever there are substitutes of the required sex who are eligible and willing to be so appointed or promoted.  Substitutes so appointed or promoted shall, however, be subject to the provisions of these rules relating to probation and permanent appointment.

12.  Upon request of the appointing or nominating officer preference in certification may be given to the wife of the superintendent of an Indian school for filling a vacancy in the position of teacher or matron in said school.

13.  Whenever there shall occur a vacancy which the public interest requires shall be immediately filled and which can not be so filled in time to meet the emergency by certification from the eligible registers, such vacancy may, subject to the approval of the Commission, be filled by temporary appointment without examination until a regular appointment can be made.  Such temporary appointment shall in no case continue longer than ninety days, and shall expire by limitation at the end of that time.  No person shall serve longer than ninety days in any one year under such temporary appointment or appointments, and in any event only until a regular appointment can be made through examination and certification.  Said year limitation shall begin to run in the case of any person on the date of his first such appointment:  Provided, That whenever an emergency shall arise requiring that a vacant position in any internal-revenue district shall be filled before a certificate can be issued by the Commission and an appointment made thereto in the manner provided in these rules such position may be filled without regard to the provisions of these rules by temporary appointment for a period not to exceed thirty days, and only for such period as may be required for the execution of the necessary details of an appointment thereto in accordance with said provisions; but no person shall receive such temporary appointment who within the ninety days next previous thereto has been separated from a position in said district to which he was temporarily appointed under the provisions of this section.

14.  Whenever a temporary appointment shall be made through certification from the eligible registers of the Commission in the manner provided in these rules, such temporary appointment shall in no case continue longer than six months, and shall expire by limitation at the end of that period.

  RULE IX.