Monopolies and trusts shall never be allowed in this state and no incorporated company, co-partnership or association of persons in this state shall directly or indirectly combine or make any contract, with any incorporated company, foreign or domestic, through their stockholders or the trustees or assigns of such stockholders or with any co-partnership or association of persons, or, in any manner whatever, to fix the prices, limit the production, or regulate the transportation of any product or commodity. The legislature shall enact laws for the enforcement of this section by adequate penalties, and in the case of incorporated companies, if necessary for that purpose, may, as a penalty declare a forfeiture of their franchises.