All persons in this State purchasing milk or cream for manufacture, sale or shipment and paying for it on the basis of the butterfat contained therein, as determined by test, shall take or cause to be taken in the places where such milk or cream is purchased or tested a representative sample of all such milk or cream, and if any be left on hand after a shipment is made, a representative sample of this shall likewise be taken. Such sample shall be not less than two ounces avoirdupois in weight and shall be immediately transferred to a clean and dry sample jar and properly sealed to prevent evaporation and the escape of any of the contents thereof. All samples of milk or cream so taken shall be plainly marked or labeled, and such mark or label shall be entered upon the records of the purchaser to correspond with the name of the person from whom such purchase was made, together with the weight of the milk or cream, if any, which is left on hand after shipment is made. Such samples shall then be protected from extremes of heat and cold and held until five P. M. of the following day, except that all such samples taken on a day preceding a holiday shall be held until five P. M. of the next day following such a holiday. During the period mentioned such samples shall be subject to inspection by the Department of Agriculture and shall be opened only in the presence of the Commissioner of said Department or his duly authorized representative. Any person violating any provision of this section shall be guilty of a misdemeanor and, upon conviction, shall be punished by a fine not exceeding one hundred dollars or by imprisonment for a period not exceeding thirty days for each and every offense so committed.