Every unrevoked certificate and indorsement of registration is presumptive evidence that the person named is legally registered. No person can register any authority to practise medicine unless issued or indorsed as a license by the regents. No such registration is valid unless the authority registered constituted at the time of registration a license under the laws of the State then in force. No diploma or license conferred on a person not actually in attendance at the lectures, institution, and examinations of the school conferring the same, or not possessed, at the time of its conferment, of the requirements then demanded of medical students in this State as a condition of their being licensed, and no registration not in accordance with this article, shall be lawful authority to practise, nor shall the degree of doctor of medicine be conferred _causa honoris_ or _ad eundum_, nor if previously conferred shall it be a qualification for practice (_ib._, s. 151). EXCEPTIONS.—The law does not affect commissioned medical officers serving in the United States army, navy, or marine hospital service while so commissioned; or any one while actually serving on the resident medical staff of any legally incorporated hospital; or any legally registered dentist exclusively engaged in the practice of dentistry; or any manufacturer of artificial eyes, limbs, or orthopædic instruments or trusses in fitting such instruments on persons in need thereof; or any lawfully qualified physician in other States or countries meeting legally registered physicians in this State in consultation; or any physician residing on a border of a neighboring State and duly authorized under the laws thereof to practise medicine therein whose practice extends into this State, and who does not open an office or appoint a place to meet patients or receive calls within this State; or any physician duly registered in one county called to attend isolated cases in another county, but not residing or habitually practising therein (_ib._, s. 152).