250 ROYAL SOCIETY OF CANADA 



Explanation of Plates. 



Figure 1. — Transverse section showing the general structure of the 

 " rope/' and the development of the central cavity, x. 9.5. 



Figure 2. — ^^Transverse section showing at pr. the parenchyma bordering 

 upon the central cavity; c. the last formed and imper- 

 fect oork layer; ab, the absciss layer which has been 

 ruptured, x 170. 



Figure 3. — Longitudinal section shoAving at pr^, the pareaichyma cells 

 of the innermost layer, which have assiuned an elongated 

 form and become mechanical cells; pr. the thick-walled 

 cells of the same region; c, the last formed and imper- 

 fectly developed layer of oork; ab, the absciss layer; 

 mr, the medullary ray. x 170. 



Figure 4. — Longitudinal section showing at pr, the elongated paren- 

 chyma cells of the innermost structure bordering upon 

 the central cavity, with pitted cells at pt, and on the 

 left (c), the last development of cork tissue, x 250. 



Figure 5. — Transverse section showing the pitted terminal walls of 

 the parenchyma cells as in Fig. 4, pt. x 250. 



Figure 6. — Transverse section from the region of the innermost paren- 

 chyma, with the outer face {of), the inner face {if), the 

 parenchyma tissue with thick walls and intercellular 

 spaces {pr), and a rudimentary medullary ray {fc). 

 X 250. 



Figure 7. — Transverse section showing the series of cork layers with 

 absciss layers, and the variations in volume of the cork 

 cells. X 170. 



^Figure 8. — Transverse section showing nodal regions of structure at 

 the end of the central cavity, together with a radially 

 developed region of modified cork devoid of absciss layers. 

 X 34. 



Figure 9. — Transverse section showing a nodal region at the precise 

 extremity of the central cavity, x 34. 



