Upon the day set for the hearing upon the original petition for the annexation of any tract or tracts of land to such district, if it shall appear to the board of directors of such district from such evidence as may be adduced by any party in interest, that the protesting petition is not signed by the requisite number of owners of lands, the board of directors of such district shall thereupon dismiss said protesting petition and shall proceed with the original hearing as provided in section 46-525.