(1) "Member" means a state employee included in the membership of the retirement system, as provided for in section 13.

    (2) "Membership service" means all service rendered after July 1, 1943.

    (3) "New member" means a person who becomes a member of this retirement system on or after January 1, 1945.

    (4) "Original member" means a person who became a member of this retirement system before January 1, 1945, or as provided in section 18.