public void initialise(World world) throws PatternFormatException
  {
    String[] cellParts = cells.split(" ");
    for (int i=0;i<cellParts.length;i++)
    {
      char[] currCells = cellParts[i].toCharArray();
      for (int j=0;j<currCells.length;j++)
      {
        if (currCells[j] != '1' && currCells[j] != '0') throw new PatternFormatException("Error: incorrect format of cell description");
        if (currCells[j] == '1') world.setCell(j+startCol,i+startRow,true);
      }
    }
  }