[PBNHALLOW] NOTES ON TERTIARY PLANTS 71 



24. a. Radial section through a resin passage showing epithelium cells on 



the left and parenchyma cells on right passing into tracheids with 

 bordered pits, x 200. 



b. Resin cells from the spring wood showing massive forms of resin. 



X 200. 



c. Resin cells from the summer wood lying radially internal to a 



tracheid with bordered pits, and showing transitional form, x 200. 

 Sequoia gigantea. 



25. Radial section showing at 



a. Cells from the spring wood filled with resin, x 200. 



b. Cells from the summer wood devoid of resin and of much greater 



length. X 200. 

 Abies bracteata. 



26. Transverse section showing nature and distribution of resin passages. 



X 46. 



27. Radial section through a resin passage showing the thick- walled 



epithelium cells on the left, immediately next to the canal, and 

 elongated wood parenchyma cells with simple pits on the right. 

 X 200. 



Abies nobilis. 



28. Transverse section showing structure and disposition of the resin 



passages, x 46. 

 Abies amabilis. 



29. Radial section showing details of resin cells, x 200. 



a. Tracheids of the wood parenchyma with bordered pits, the lower 



end coterminous with the upper end of 



b. Resin cells of the ordinary type, with simple pits. 



