series of plants can not be made advantageously in the field. For the shorter transects, meter sizes of centimeter plotting paper can often be used to advantage. In this event, the topographic line is drawn to the scale of 10 : 1 and the series of plants transferred directly to it. In the case of transects between 10 and 100 meters, the scale of the drawing is increased from 1000 : 1 to 100 : 1, so that each decimeter of the original series is compressed into a centimeter. For the longest transects, corresponding reductions must be made, but in these it will be remembered that the series is plotted by meter instead of decimeter. [Illustration: Fig. 55. Line transect running east and west in the _Picea-Pinus-hylium_, showing the relation of the herbaceous layer to the _Carex-Catha-helium_, invading along the brook; ecotones at _e_.] =219. The location and size= of line transects are determined by the purpose for which they are designed. Short transects are valuable for detail, but they can be used to advantage only where changes in arrangement are taking place rapidly. They are especially adapted to the study of minute alternations and to the zonation of small ponds, streams, ditches, roads, blowouts, etc. Longer transects can not furnish the same detail, on account of the amount of time necessary, but they are invaluable for the zonation and alternation of larger areas, such as the consocies, formation, and formation series. They are of particular importance for the record of zonation, since they afford a clue to the topographic symmetry of the area. The location of a transect depends upon the area to be studied, though it should always run through a portion as typical as possible. The general direction is ascertained by means of the compass, and when there is a measurable difference in elevation it is taken by the barometer or otherwise. The points at which ecotones cross the transect are carefully indicated upon the chart. They serve as stations for simultaneous readings of physical factors, though in the majority of cases water-content readings alone will determine the reason for the ecotone. Photographs of line transects should be made while the tape is in position, in order that the superficies of the series may be as evident as possible. _The Belt Transect_