76 THE ROYAL SOCIETY OF CANADA 



Case 11. (figure 14). Complete ascidium on one side, (internal 

 lobe) on the other complete suppression of distal segment of internal 

 lateral lobe. External lobes partially differentiated. 



Case 12. (figure 15). An ascidium within which is a second, but 

 imperfect one, indicated by a fold of tissue bridging the mid-vein, 

 continued as a slight cicatrix on the left, and morphologically a unit 

 with the sinuses on the margin. 



Considering the above series of cases as a whole, the following 

 may be stated. 



All the abnormal form-expressions are of the same kind, differing 

 only in degree. The minor expressions take the form of shallow 

 sinuses and corresponding folds in the blade. In place of a pair of 

 folds, a single one, forming a ridge of tissue may traverse the mid- 

 vein. When opposite sinuses meet, an ascidium results. The 

 occurrence of sinuses and folds is accompanied by limited transverse 

 growth. The leaf-margins bordering a sinus may be free although the 

 sinus itself is closed. The morphological lower surfaces are then 

 continuous for some distance, as if originally free lobes had fused. In 

 some instances the free margins occur only toward the base of the leaf 

 and not above (figure 13), though a ridge of tissue usually enables 

 the observer to trace the morphological relation to a sinus. (Figure 

 9). One recognizes in these free laminar edges the "enations," of 

 which many examples are given by Worsdell.^ In these instances, 

 the enations are the continuations of the leaf margins from the sinu.ses, 

 and they may be transverse wâth respect to the mid-vein (of the lobe) , 

 or may run longitudinally, apparently above a mid-vein. But this 

 latter appearance is deceiving, since the vein belongs to the lobe to 

 which one of the free leaf-margins pertains, and not to the other, 

 figure 7a, 9a-c). In fact the ridge on occasion diverges widely from the 

 vein, returning to it again (figure 8-8b). These enations are therefore 

 not laminar outgrowths from a vein, but are the edges of adjacent 

 lobes, concrescent^ by their lower surfaces. In the cases before us 

 therefore, enations and ascidia are somewhat difrerent expressions 

 of the same phenomena — unequal growth responding to the external 

 and internal conditions imposed. The external conditions were, as 

 aforesaid, severe drought causing pot-binding, almost complete cessa- 

 tion of growth and consequent dwarfing of outer parts and induration 

 of exposed parts of buds, alternating with abundance of water and 

 higher temperatures with consequent sudden growth of included 



iWorsdell, W. C. The Principles of Plant Teratology', Vol. 1, London; The" 

 Ray Society, 1915. This volume supersedes the earlier publication of Masters. 

 ^Congenitally concrescent, as defined by Gœbel, I.e., Vol. 1, p. 53. 



