36 



EDWARD C. JEFFREY ON 



Explanation of Plates. 



(All the figures are from photomicrographs.) 

 PLATE 1. 



Fig. 1. Transverse section through the margin of the traumatic wood in Pseudotsuga taxifolia. X 20. 



Fig. 2. Transverse section of the root of P. taxifolia. X 20. 



Fig. 3. Transverse section of the lower third of the leaf of P. taxifolia. X 40. 



Fig. 4. Transverse section of a stem of P. taxifolia, showing the exit of the leaf trace from the central cylinder. X 60 

 Fig. 5. Transverse section of the stem of P. taxifolia, showing the structure of the leaf trace in its passage through 

 the cortex, x 60. 



Fig. 6. Transverse section of the root of Larix americana, showing the communication of the resin ducts, opposite 

 the groups of protoxylem, with the ducts of the cortex. X 60. 



Fig. 7. Transverse section through the leaf base of L. americana, showing the double trace. X 60. 



Fig. 8. Transverse section through part of a wounded stem of Picea nigra, showing the formation of traumatic resin 

 canals. X 10. 



PLATE 2. 



Fig. 9. Transverse section of the stem of Picea nigra, showing the double leaf trace. X 60. 



Fig. 10. Transverse section of a wounded stem of Abies balsamea, showing the formation of traumatic resin canals 

 along the margin of the wood. X 8. 



Fig. 11. Part of the same more highly magnified to show the details of the resin canals. X 30. 



Fig. 12. Traumatic wood of the base of a witches' broom of A. balsamea, showing the formation of resin canals. 



X 30. 



Fig. 13. Section of the injured wood of the stem of A. magnifica, showing the formation of numerous rows of resin 

 canals in the same annual ring. X 60. 



Fig. 14. Transverse section through the upper part of the axis of the cone of A. magnifica, showing the presence of 

 normal resin canals in this organ. X 20. 



Fig. 15. Section through part of the lower region of the cone-axis of A. magnifica, showing the smaller size of the 

 resin canals. X 30. 



Fig. 16. Section through part of the same region as that shown in Fig. 14 more highly magnified to show the fusion of 

 the resin canals. X 40. 



PLATE 3. 



Fig. 17. Section through a vigorous branch in the reproductive region of Abies magnifica, showing the presence of 

 normal resin canals in the first annual ring. X 20. 



Fig. 18. Section through another specimen more highly magnified to show the normal occurrence of resin canals in 

 the first annual ring. X 20. 



Fig. 19. Section through a vigorous yearling branch of A. magnifica, showing the presence of normal resin canals. 

 X20. 



Fig. 20. Transverse section of the inner portion of the last, highly magnified to show the structure of the resin canals. 

 X 180. 



Fig. 21. Longitudinal section of the pith of A. magnifica, showing the presence of sclerified diaphragms similar to 

 those of the Cordaites. X 25. 



