(a) Immediately upon the adjournment of the creditors' meeting the clerk and the assignee, if any is chosen at the meeting, shall proceed to make and return to the district court an inventory and appraisement of the entire estate assigned.
(b) From time to time, the assignee shall file in the court an additional inventory and valuation of any property coming into his hands after the filing of any former inventory, which shall be treated as a part of the original inventory and appraisement.