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THE ROYAL SOCIETY OF CANADA 



to the base of the blade, but diverging some distance from the vein as 

 the base is approached. Section through a-b, shown in figure 8a; 

 through c-d in figure 8b. The network of veinlets was developed in 

 disregard of this ridge, as if the morphological lower moiety of the 

 blade were a continuous structure; the discontinuity of the palissades 

 of the concrescent lobes clearly indicated, and the palissade cells 

 along the ridge show disarrangement and more or less collapse. The 

 concrescence thus appears to have been antecedent to the develop- 

 ment of the veinlets. 



Case 8. (figure 9). This case is comparable to case 1, but is com- 

 plicated by an attempt to form two ascidia (at the points indicated by 

 arrows) in series in the chief lobe and to form an ascidium of the 

 internal lobe on the right. External lobes not differentiated. Figure 

 9a, section through a-b; 9b, through c-d; 9c, through e-f; cr, the right 

 hand margin of the chief lobe; the arrow point indicates the blade of 

 the internal lobe; x, the morphological left-hand margin of the right 

 hand external lobe. The regions through which the sections were 

 taken is therefore a double cicatrix. 



Case 9. (figure 10). An ascidium on an internal lobe (and distant 

 from the blade), complete but for an open canal above the vein. The 

 border of the canal, formed by the leaf margin, is continuous on the 

 left but not so on the right. The constriction appears due to lateral 

 pressure, the absence of longitudinal pressure accounting for the 

 absence of a transverse fold to close the ascidium. Figure 10a, 

 section through a-b. 



