Section 172. Co-respondent as party

1. In an action brought to obtain a
  divorce on the ground of adultery the plaintiff or defendant may serve a
  copy of his pleading on a  co-respondent  named  therein.  At  any  time
  within  twenty  days after such service, the co-respondent may appear to
  defend such action so far as the issues affect him. If no  such  service
  be  made,  then at any time before the entry of judgment a co-respondent
  named in any of the pleadings may make a written demand on any party for
  a copy of a summons and a pleading served by such party, which  must  be
  served  within  ten  days  thereafter,  and he may appear to defend such
  action so far as the issues affect him.
    2. In an action for divorce where a  co-respondent  has  appeared  and
  defended,  in case no one of the allegations of adultery controverted by
  such co-respondent shall be proven, such co-respondent shall be entitled
  to a bill of costs against the person naming him as such  co-respondent,
  which  bill of costs shall consist only of the sum now allowed by law as
  a trial fee, and disbursements.