ANATOMY AND PHYLOGENY OF THE CONIFEKALES. 457 



ducts, such as prevail in the Abietineae of the present day. It may be urged that this in 

 itself 'is a very small point. Reply may be made that the mesarch structure of the pri- 

 mary woody bundles of the more primitive Gymnosperms and the adhesion of the stamens 

 to the calyx in the Ro.mceae are likewise small points, yet no well informed botanist 

 doubts that they are important taxonomic criteria. It appears to be rather the signifi- 

 cance than the magnitude of anatomical or morphological features whicli makes them of 

 classificatory value. The peculiar and apparently most significant mode of occurrence of 

 resin canals in the wood of the Sequoias points to their derivation from an Abietineous 

 stock, which may of course have been ancestral not only to the Sequoias but also to the 

 li^dng genera of the Abieti7teae as well. This conclusion appears to he supported by a 

 consideration of the structure of the female cone in the Ahietineae, Taxodineae, and the 

 Coniferales in general. Finally the derivation of the Sequoias from an Abietineous source 

 is in no way contradictory to the palaeontological record. 



Summary. 



1. Typical resin ducts occur in the wood of the peduncle, axis, and scales of the 

 female cone of Sequoia gigcmtea. 



2. Resin ducts are likewise present in the first annual ring of vigorous branches of 

 adult trees of the same species. Resin ducts are normally absent in all the branches of 



immature trees. 



3. Resin ducts are also found in the leaf traces of very vigorous leaves of adult 



trees of Sequoia gigantea. 



4. Resin ducts are entirely absent from the wcjod of all parts of the cones of Sequoia 



sempervirens. 



5. The same statement holds true of the branches and leaves of this species. 



6. Resin ducts appear in tangential rows in the wood of root and shoot in both 

 Sequoia gigantea and Sequoia senvpervirem as a result of injury to the tissues. 



7. A consideration of the mode of occurrence of resin ducts in the Sequoias leads to 

 the conclusion that they are an ancestral feature of structure in the wood. 



8 The anatomy of the vegetative organs and floral organs of the living Sequoias 

 points strongly to their derivation from an Abietineous stock. This conclusion receives 

 confirmation from what is known of tlie anatomy of the fossils, and finally is not in 

 contradiction to the palaeontological record. 



For help in securing the material for the present investigation, I wish to offer 

 my best thanks to Miss Alice Eastwood, Sir William Thiselton-Dyer, Dr. A. A. Lawson, 



