Section 9. Oath of office; eligibility of commissioners and officers

Each
  commissioner and each person appointed to office by the chairman  shall,
  before  entering  upon  the duties of his office, take and subscribe the
  constitutional oath of office. The oaths of office other than those of a
  commissioner shall be filed in the office of the commission.  No  person
  shall   be  eligible  for  appointment  or  shall  hold  the  office  of
  commissioner or be appointed to, or hold, any office or  position  under
  the  commission,  who  holds  any  official  relation  to  any person or
  corporation subject to the supervision of the commission,  or  who  owns
  stocks or bonds of any such corporation.