Section 6556. Special provisions

1. Any chiropractor who holds a license
  stating that the holder is not authorized to use X-ray in  his  practice
  shall  on each registration, continue to obtain a license so marked. Any
  chiropractor holding such a license may obtain a license permitting  the
  use  of  X-ray  provided  he  first passes an examination in the use and
  effect of X-ray satisfactory to the board and the department.
    2. An applicant who graduated from a school of chiropractic  prior  to
  January  first,  nineteen hundred sixty-eight need not meet the two-year
  preprofessional college study requirement provided  for  in  subdivision
  two of section sixty-five hundred fifty-four.