Whenever a position in the competitive classified civil service is to be filled, the appointing authority shall notify the commission of that fact, and the commission shall certify the names and addresses of the 3 candidates standing highest on the eligible list for the class or grade to which such position belongs, and the appointing authority shall forthwith appoint to such position one of the 3 persons so certified. Such appointment shall be for a probationary period to be fixed by the rules, but not to exceed 6 months. At or before the expiration of the probationary period, the appointing officer may, by presenting specific reasons for such action in writing, discharge a probational appointee, or, with the approval of the civil service commission, transfer him to another department. If not discharged prior to the expiration of the period of probation and if no complaint has been made as to the service rendered, the appointment shall be deemed complete. To prevent the stoppage of business or to meet extraordinary conditions or emergencies, the head of any department or office, may with the approval of the commission, make a temporary appointment to remain for not exceeding 60 days, or until regular appointment under the provisions hereof can be made.

   War veterans shall have 10 points added to their earned ratings who have an honorable discharge from any branch of the armed forces in time of war, and 15 points shall be added to the earned ratings of all honorably discharged veterans who have served in time of war and have a service connected disability if all other requirements of this act have been complied with by such war veterans.