=223.= The denuded transect bears exactly the same relation to a permanent one as that which exists between the denuded and the permanent quadrat. While the permanent transect records the actual mutations due to changing physical factors or to competition, the denuded transect throws needed light upon the mobility and ecesis of the various species, and upon the nature of the competition between them. Denuded transects may be established wherever it seems desirable, after the strip has been properly charted and photographed. The most valuable results, however, are secured by locating each one alongside of a permanent one. The best plan is to locate and chart two permanent transects a meter apart. A single view is then made of the two. One of them is denuded together with a strip 2 decimeters on either side, resulting in a denuded transect 5 decimeters wide. In charting this during succeeding years, the entire width may well be plotted as long as the vegetation is open, but after it has again become well established, it is necessary to save time by confining one’s attention to the central decimeter strip. Photographs can be made either of the permanent and denuded transects singly, or of the two together. The latter method has certain obvious advantages. Climatic factor readings can be made for both transects in common, but all those factors which are affected by the exposure of the soil surface must be observed in each. _The Layer Transect_ =224.= This is a modification of the line transect, by means of which the vertical relations of plants are also shown, especially the tendency to form layers which is so regular a feature of forest formations. Owing to the difficulty of charting in three planes, belt transects do not lend themselves to this purpose. Because of the greater complexity, layer transects can rarely exceed ten meters in length except in those formations where layering is little or not at all developed. The simplest method is to establish a line transect in the ordinary way, and then to record the height of each plant as its position is noted. This is done by means of a measuring stick ruled in decimeters, which can be moved from interval to interval along the tape, or better, by two such sticks connected by tapes a meter long at every five decimeters of the sticks. These should be two meters high for woodland, and one meter for grassland. Layer transects often run on even surfaces, but if this is not the case, the usual data for a topographic map should be taken. The final chart is constructed on the scale of 10:1, the height of each plant being indicated by a vertical line equal to .1 of the observed height. A photograph of a representative meter of the transect is taken when the measuring sticks and rods indicated above are in position. Physical factor readings, principally of light, but often also of humidity, temperature, and wind are made at the height of the various layers when these are present.