(a) by commissioned medical officers in the armed forces of the United States or in the United States public health service while on active duty in the respective service; or,

(b) by any one actually serving as a member of the resident medical staff of any legally incorporated hospital; or,

(c) by any person duly licensed to practice as a physician or surgeon in this state. 2. A person who holds a license as a funeral director, undertaker or embalmer, as defined herein, and is registered as required herein, shall be entitled to practice as defined and limited by the provisions of the law at the time the license was issued, except as otherwise provided by this article. 3. Notwithstanding the foregoing provisions of this section, the commissioner may in his discretion enter into an agreement with another state of the United States or a province of the Dominion of Canada, pursuant to which agreement any person, duly licensed and registered as a funeral director, undertaker or the equivalent thereof by and in such other state or province, may enter into this state for the sole purposes of removing to such other state or province dead human bodies, supervising the delivery to or removal from a common carrier of such bodies, or burying, cremating, or supervising funeral services over dead human bodies brought from such other state or province as though such person were duly licensed and registered by and in this state except that such person shall not maintain an establishment, advertise or hold himself out directly or through any agent or agency or otherwise as a funeral director, undertaker or the equivalent thereof other than in the state or province in which he is registered and licensed.