56 ROYAL SOCIETY OF CANADA 



Fig. 5. — Sequoia semper vir ens. Tangential section, showing the very broad ray- 

 cells. X 210. 



Fig. 0. — Taxodium disiichum. Radial section through a medullary ray, showing 

 the form of the cells and the nature of the pits on the lateral walls. 

 X 210. 



Fig. 7. — Tsuga Mertensinna. Transverse section through the summer wood, show- 

 ing a single resin-cell on the outer face. 



Fig. 8. — Tsuf/a canadensis. Radial section, showing the strongly pitted terminal 

 walls of the ray-cells, x 210. 



Fig. 9. — Pseudotsuga Douglasii. Tangential section, showing the structure of the 

 fusiform ray, the rcsin-passage showing thick-walled epithelium cells. 

 X 210. 



Fig. 10. —Pseudotsuga Douglasii macrocar2Ja. Radial section of a medullary ray, 

 showing the character of the terminal walls and the pits on the lateral 

 walls. X 210, 



Fig. \\.—Larix americana. Transverse section through the summer wood, showing 

 a single resin-cell distinguished by exposure of the pitted terminal 

 wall, X 210. 



Fig. 12. — Picea alba. Radial section of a medullary ray, showing the nature of the 

 terminal walls, and tracheids limiting the ray above and below x 210. 



Plate III. 



Fig. 1. — Larix aniericanii. Tangential section of a medullary ray, showing resin- 

 ous thick-walled cells and the resin-passages with thick-walled epi- 

 thelium. X 210. 

 Fig. 2. — Picea nigra. Tangential section of a medullary ray, showing characteristic 



features of structure, x 210. 

 Fig. 3. — Finns albicaulis. Tangential section of a fusiform ray, showing charac- 

 teristic features of structure, the resin-passages with thyloses and rather 

 thin-walled epithelium cells, x 210. 

 Fig. 4. — Pinus palusfris. Tangential section of a fusiform ray, showing one aspect 

 of structure in which the very thin-walled cells have been broken out. 

 X 210. 

 Fig. 5. — Pinus reflexa. Radial section of a medullary ray, showing characteristic 

 features of the first section of the genus Pinus ; the lateral walls of the 

 cells with very large pits, the rays limited above and below, by trach- 

 eids. x 210. 

 Fig. 6, —Pinus refiexa. Tangential section of a fusiform ray, showing the large, 



thin-walled cells and the imperfectly formed resin-passages, x 210. 

 Fig. 1.— Pinus serotina. Radial section of a medullary ray, showing characteristic 

 features of the second section of Pinus ; the high cells with lenticular or 

 oval pits, the limiting tracheids above and below with strongly dentate 

 walls. X 210. 

 Fig. 8.— Pinus clausa. Tangential section of a fusiform ray, showing characteristic 



features of structure, x 210. 

 Fig. 9. -Pinus Paf four iana. Radial section of a medullary ray, showing charac- 

 teristic features of structure of the second section of Pinus ; the walls 

 of the limiting tracheids edentate, x 210. 

 Fig. 10.— Pinus cubensis. Tangential section of a medullary ray, showing one aspect 

 of the ordinary rays ; the parenchyma cells both thick and thin-walled, 

 the terminal tracheids high, oblong, x 210. 



