1. Experimental investigations are of interest in connection with woody plants both from a general biological point of view, and also from the standpoint of plant pathology. They are also of interest because they suggest the possibility of producing ornamental woods experimentally. 2. Three types of rays, aggregate, compound, and diffuse, which persist contemporaneously in Casuarina, are characteristic of angiospermous trees. The aggregate seems to be the more primitive one, from which the diffuse and compound have been derived by different processes of evolution. 3. Wound reactions in woody forms must be considered with reference to the conservative regions, the seedling structures, and fossil record, because only those structures occurring as a consequence of injury which have parallel conditions in these parts can be regarded as true reversions. 4. Work on living and extinct Gymnosperms has established certain principles on the basis of which experimental investigations in angiospermous woods may proce...