The director of public service shall have entire charge and control of receipts from the sale of cemetery lots, and of laying off and embellishing the grounds. He may receive donations by bequest, devise, deed of gift, or otherwise, or money or other property, the principal or interest of which is to be used for the enlargement, improvement, embellishment, or care of the cemetery grounds generally, or for any particular parts or lots therein, as the donor directs, or as the director determines if no such direction is given. The director shall sell lots, receive payment therefor, direct the improvements, and make the expenditures under such rules and orders as he prescribes, and shall invest, manage, and control property received by donations and surplus funds in his hands from any source.