A psychiatrist under the meaning of the foregoing sections and section 22-a and 22-b of chapter 14 of this act is a physician, duly licensed to practice in the state of Michigan, who has had at least 5 years experience in actual practice, including either (a) 3 years’ full time practice since January 1, 1933, in the care and treatment of persons suffering from nervous or mental disease or mental defect, in an institution provided for the care of such persons, or (b) has devoted 5 years prior to the case in which his services are requested, to a practice confined wholly or substantially to the diagnosis, care or treatment of persons suffering from nervous and mental disease or mental defect. If no qualified psychiatrist is immediately available for the purposes of aiding the court in any investigation under the foregoing sections or section 22-a and 22-b of chapter 14 of this act, the nearest state hospital shall be required to furnish, upon request of the court, without charge, a competent psychiatrist within the meaning of this act.