ANATOMY AND PHYLOGENY <>F T1IK CONIFERALES. 



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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 Romceae 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 which 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 

 living genera of the Abietineae as well. This conclusion appears to be supported by a 

 consideration of the structure of the female cone in the Abietineae, 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 (jigantea. 



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 wood 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 semjjervirens 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 the 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 Thisel ton-Dyer, Dr. A. A. Lawson, 



