The directors may from time to time, in respect of shares having a par value, make calls upon the members in respect of any money unpaid on their shares, whether on account of the nominal value of the shares or by way of premium, and not by the conditions of allotment thereof made payable at fixed times and each member shall, subject to receiving at least 30 days' notice specifying the time or times and place of payment, pay to the corporation at the time or times and place so specified the amount called on his shares.