Valuation of undisclosed assets determines taxable basis; prescribed bases apply to debts, goodwill, agency rights, and other assets. The rule treated the value of an asset not disclosed in the balance sheet as the taxable basis, prescribing that debts be valued at the amount due (reduced if previously deducted under income-tax), that purchased goodwill and managing-agency rights be valued at the lesser of market value or purchase price, and that any other asset be valued at market value on the valuation date.