(60) After an answer is put in, it may be amended, as of course, in any matter of form, or by filling up a blank, or correcting a date, or reference to a document or other small matter, and be resworn at any time before a replication is put in or the cause is set down for a hearing upon bill and answer. But after replication or such setting down for hearing, it shall not be amended in any material matters, as by adding new facts or defenses, or qualifying or altering the original statements, except by special leave of the court, or of a judge thereof, upon motion and cause shown, after due notice to the adverse party, supported, if required, by affidavit. And in every case where leave is so granted, the court or the judge granting the same may, in his discretion, require that the same be separately engrossed, and added as a distinct amendment to the original answer, so as to be distinguishable therefrom.