All fraternal societies incorporated under the laws of this state, or operating herein, or whose principal place of business is in this state, shall provide a separate fund from which to pay expenses, which shall not exceed for established societies more than twenty percent (20%) of total collections, nor more than twenty-five percent (25%) during the period of organization. Where practicable, the mortality funds shall be kept separate from other funds and be used only for the purpose of paying death benefits.