340 



THE ANATOMY OF WOODY PLANTS 



Further, an investigation of the first annual ring of the stem in 

 trees which have attained such vigor of development as to pro- 

 duce seed often 

 shows the pres- 

 ence of resin canals 

 such as are not 

 normally found in 

 the subsequent an- 

 nual increments of 

 growth (Fig. 248). 

 Finally, the fibro- 

 vascular strand of 

 the leaf frequently 

 contains in the 

 region of the xylem 

 a single resin canal. 

 The occurrence of 

 ligneous resin 

 canals in the van- 

 primitive re- 



FIG. 247. Transverse section of reproductive axis 

 of Sequoia gigantea, showing resin canals in the wood. 



OUS 



gions indicated 

 above is good evi- 

 dence of the origi- 

 nal presence of 

 such structures in 

 the woody tissues 

 of Sequoia. Addi- 

 tional information 

 on this subject is 

 furnished by the 

 wound reactions of 

 the genus. In 

 either of the two 

 species, S. gigantea 

 or S. sempervirens, 

 the infliction of 

 wounds may be 



FIG. 248. Twig of Sequoia gigantea, showing pres- 

 ence of resin canals in the first annual ring. 



