Such mutual insurance corporations shall, annually, set aside and maintain as a reinsurance reserve, an amount equal to ten percent of the receipts from assessments, or premium payments, during the year until the total amount thus accumulated shall equal forty percent, but not to exceed fifty percent of the amount of the annual assessment, or premium payment, at the rate charged for such insurance on all policies in force. The reserve thus accumulated may be used for the payment of losses and expenses, and when so used shall be restored and maintained in like manner as originally accumulated.