Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 94, § 49

Whoever himself or by his agent sells, exposes for sale or has in his possession with intent to sell oleomargarine shall have the word “oleomargarine”, “margarine”, or “butterine” so stamped, labelled or marked that said word cannot be easily defaced, upon the top, side and bottom of each tub, firkin, box or package containing any of said oleomargarine.  Whoever, himself or by his agent, exposes or offers for sale oleomargarine not in the original packages shall attach thereto in a conspicuous place a label bearing the words “imitation butter”, or the word “oleomargarine”, “margarine”, or “butterine”.  In retail sales of oleomargarine not in the original package the seller shall attach to each package so sold, and shall deliver therewith to the purchaser, a label or wrapper bearing in a conspicuous place upon the outside of the package the words “imitation butter”, or the word “oleomargarine”, “margarine”, or “butterine”.  Each such stamp, label or mark shall be in printed letters in a straight line of not less than twenty point plain gothic type.  This section shall not apply to oleomargarine served with or as a part of a meal.