The power and authority of regulating railroad freight and passenger tariffs, the locating and building of passenger and freight depots, correcting abuses, preventing unjust discrimination and extortion and requiring reasonable and just rates of freight and passenger tariffs, are hereby conferred upon the legislature, whose duty it shall be to pass laws from time to time regulating freight and passenger tariffs, to prohibit unjust discrimination on the various railroads, canals, and rivers of the state, and to prohibit the charging of other than just and reasonable rates and enforce the same by adequate penalties.