A mutual savings bank may invest its funds in loans to banks or trust companies which mature on the next business day following the day of making such loan. The loans may be evidenced by any writing or ledger entries deemed adequate by the mutual savings bank and may be secured or unsecured. The loans made hereunder are payable on the same basis as are regular deposits in such banks, and therefore the transactions may be characterized for accounting and statement purposes and carried on the books of the mutual savings bank as either a deposit with or a loan to the bank.