The Milk Commission shall prepare and adopt a system of accounting designed to show, for each distributor of milk and milk products, under the supervision of the Commission, the total purchases by any distributor of each grade or class of milk; the total sales by each distributor and the revenue therefrom, for each grade or class of milk and the quantity thereof. Such accounting system shall be designed to show total purchases including the respective grades or classes of milk bought, as well as the total sales and the respective classes or grades of milk sold.

Each distributor of milk and milk products under the supervision of the Commission shall adopt and use the system of accounting adopted by the Milk Commission. The books and records of each distributor shall be open to inspection by the Commission or its agents during regular business hours, and shall be audited by it at such regular intervals as shall be prescribed by the Milk Commission.

It shall be unlawful for any distributor to pay for milk upon any such basis of grade or class lower than that upon which such milk is sold or used by him. Nothing herein shall prevent the sale of a grade or class of milk by a distributor as milk of a lower grade or class. It shall be unlawful for any distributor to fail to use the system of accounting herein prescribed or refuse to allow the same to be inspected or audited.