_Dendrological Studies._ Dendrological studies include studies in tree distribution and wood identification. For each tree species growing in the United States (and there are about 500 of them) it is desirable to know its geographical distribution, its commercial distribution, and its local distribution. The first of these deals with the entire range of the tree by geographical divisions; the second of these with the distribution of those bodies of timber that are of commercial quantity or size; and the last deals with the distribution of the tree by local divisions, such as lowlands, slopes, ridges, valleys, plateaus, etc. This information is usually placed on maps for permanent record. Observations by Forest officers on the many National Forests are recorded by them and at the first opportunity sent to Washington. Very often it happens that the range of a species of tree is considerably extended and that a tree is found growing in a locality where it was never reported from before. The identification of woods is done at the Forest Products Laboratory. The distinguishing characteristics of the woods of many American tree species have been determined. The wood of different trees is studied under the microscope to discover in what way it differs from other woods closely related. Many such results are published for the benefit of both the lumber dealer and the general public in the form of bulletins. Both the subject of dyewoods and that of the many woods now sold as mahogany have been investigated in this way. The resulting data have been used by many companies and have helped to protect the public from frauds.