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 



FIG. 247. Transverse section of reproductive axis canals in the vari- 

 of Sequoia gigantea, showing resin canals in the wood. ^^ primitive re- 



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, 5. gigantea 

 or 5. sempervirens, 

 the infliction of 

 wounds may be 



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

 ence of resin canals in the first annual ring. 



