The statute necessarily interferes with the right of contract between the employer and employees, concerning the number of hours in which the latter may labor in the bakery of the employer. The general right to make a contract in relation to his business is part of the liberty of the individual protected by the 14th Amendment of the Federal Constitution. Under that provision no state can deprive any person of life, liberty, or property without due process of law. The right to purchase or to sell labor is part of the liberty protected by this amendment . . .