ANATOMY AND PHYLOGENY OF THE CONIFER ALES. 440 



and from the root as well, except in the axial primary wood as jusl mentioned above. 

 In all cases where 1 have been aide to make the experiment, however, I have succeeded 

 in bringing about the formation of resin canals as a result of injury, in the wood of 

 species of Abies which are normally without them, even in their reproductive axis. It 

 is interesting- in this connection to note that certain fungous discuses causing injury to 

 the wood of species of Abies produce the same result. It seems necessary to record the 

 traumatic reactions of the woody tissues of the genus Abies because, as I shall attempt to 

 show at the end of this essay, they supply an interpretation of the similar phenomena 

 in the case of Sequoia. 



The Leaf of S. gigantea. 



In figure 23, plate 70, is seen part of "a section through the base of the leaf of S. 

 gigantea. In the center of the figure lies the leaf trace flanked by the two lateral wings 

 of transfusion tissue, which are so characteristic of the lower part of the foliar bundle 

 in Sequoia and its allies. Above and below the leaf trace are masses of collenchyma- 

 toid tissue. The feature of greatest interest in the figure is, that contrary to other 

 described coniferous leaf traces, the foliar bundles of S. gigantea contain a resin duct. 

 The duct is quite of the normal type and is surrounded by a single, almost complete row 

 of resiniparous cells. In some cases, however, as is often found in the resin canals of the 

 Sequoias, the parenchymatous lining of the canal is far from being continuous, and the 

 tracheids as a result often abut directly on its lumen. It must not be supposed that resin 

 ducts occur in all the leaf traces of S. gigantea, for this is not the case. They appear 

 only to be present in the bundles of the very large leaves of exceptionally vigorous 

 branches of mature trees (i. e., trees which have already ripened seed) . All the material 

 which I have, showing this feature, came from the Gray herbarium of Harvard univer- 

 sity ; but in spite of the necessarily bad condition of preservation consequent on its 

 origin, there seems to be no reasonable doubt as to the nature of the canals, which I have 

 described above as resin ducts. The longitudinal range of the resin ducts of the foliar 

 bundles of the largest leaves in mature trees of Sequoia gigantea is quite limited; for 

 they appear only after the leaf trace has passed quite out into the cortex of the branch, 

 and indeed after it has traversed a considerable part of its upward and outward course. 

 There is as a consequence no communication between the resin ducts of the first annual 

 ring of wood in the branches and those appearing in the leaf traces. Like the other 

 modes of occurrence of resin canals described above, there is an entire absence of correla- 

 tion with other similar tissues. The resin ducts of the leaves disappear again very shortly 



