The corporations shall not control or attempt to control the relationship existing between a member and his physician and shall not restrict the right of a member to obtain the service of any licensed doctor of medicine. Any hospital which shall contract with a corporation for the furnishing of hospital care shall accept a member of the corporation with the physician of his choice in charge of his treatment at the hospital, provided the acceptance is in conformity with the hospital's regular rules of admission; provided, further, that the physician is otherwise acceptable for practice in said hospital.