Section 12. The chief justice of the land court department may appoint one or more examiners of title who shall be attorneys at law and he may also appoint a chief title examiner who shall perform all the duties of an examiner of title and such other duties in connection with the work of the court as the chief justice or justice may assign. Any deputy recorder appointed under section six, who is designated for the purpose by the chief justice by a writing filed in the recorder’s office, shall in case of absence, sickness or disability of the recorder, or if a vacancy exists in the office of the recorder, perform all of the official duties of the recorder. In case of the absence, sickness or disability of both the recorder and any deputy recorder designated to perform the official duties of the recorder, or of the recorder alone, if a vacancy exists in the position of the deputy recorder designated to perform the official duties of the recorder, the chief title examiner under the title of deputy recorder shall perform all of the official duties of the recorder.