Provided always, that nothing herein contained shall extend to authorize Her Majesty to create any new restriction in the practice of medicine or surgery, or to grant to any of the said corporations any powers or privileges contrary to the common law of the land or to the provisions of this Act, and that no such new charter shall in anywise prejudice, affect, or annul any of the existing statutes or byelaws of the corporations to which the same shall be granted, further than shall be necessary for giving full effect to the alterations which shall be intended to be effected by such new charters and by this Act in the constitution of such corporation.