orders.] If the board of directors shall deem it not to be for the best interests of the district to include thereunder the lands mentioned in the petition, such board shall by order in writing reject the petition; but if the board shall deem it for the best interests of the district to include such lands it may by order so change the boundaries of the district as to include therein the lands mentioned in the petition. If such lands are so included the order shall describe the entire boundaries of the district with such lands so included, and for that purpose the board may cause a survey to be made of such portion of such boundaries as may be deemed necessary.