Where, in the opinion of the Registrar, an applicant is in default in the prosecution of an application filed under this Act or any Act relating to trade marks in force prior to the commencement of this Act, the Registrar may, by notice require the applicant to remedy the default within a time specified and after giving him, if so, desired, an opportunity of being heard, treat the application as abandoned, unless the default is remedied within the time specified in the notice.