Section 13D. Whoever himself or by his servant or agent sells, offers for sale, exchanges or delivers or has in his custody or possession with intent to sell, offer for sale, exchange or deliver any milk designated as any grade established under authority of section twelve, and not conforming to any standard adopted for such grade, or any milk in any city or town, the board of health whereof has adopted under authority of section thirteen E bacterial standards for any grade of milk, and not conforming to such standards, or in any way violates any rule or regulation adopted and approved, or amended, under said section twelve, shall be punished by a fine of not more than fifty dollars; provided, that for a subsequent offence within one year thereafter the punishment shall be by a fine of not less than one hundred nor more than two hundred dollars.