Section 18. Whoever himself or by his servant or agent sells, exposes for sale, or has in his custody or possession with intent to sell, milk labelled as to its fat content which, upon analysis, is found to contain less milk fat than is stated upon the label, cap or tag, and whoever himself or by his servant or agent sells, exposes for sale or exchange, or delivers milk not wholly produced in the commonwealth in containers bearing, upon a label, cap, tag, or otherwise, words indicating that such milk was produced in the commonwealth, and whoever in any manner represents that milk not wholly produced in the commonwealth was wholly produced therein, shall be punished for the first offence by a fine of not more than fifty dollars, for the second offence by a fine of not less than fifty nor more than one hundred dollars, and for a subsequent offence by a fine of not less than one hundred nor more than two hundred dollars.