That no member of the legislative assembly shall hold, or be appointed to, any office which shall have been created, or the salary or emoluments of which shall have been increased, while he was a member, during the term for which he was elected, and for one year after the expiration of such term; but this restriction shall not be applicable to members of the first legislative assembly; and no person holding a commission or appointment under the United States, except postmasters, shall be a member of the legislative assembly, or shall hold any office under the government of said territory.