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THE ROYAL SOCIETY OF CANADA 



abscission activity being confined to three days. During these three 

 days, there is little or no growth, and this results from the direct 

 limitation of the water-supply by the disruption of the vascular tissues. 



Fig. 5. Successive stages of histolysis seen during the progress of abscission. 

 Semi-diagrammatic. The arrow-points are directed distally. 



(a)' Longitudinal cell walls have softened and are beginning to lengthen; 

 transverse septa have appeared. 



(b) Elongation of these walls is marked and separation has begun. Two rows 

 of cells are involved. 



(c) Separation is complete, and living cells have been set free. Remains of the 

 original primary and secondary cell walls are evident in both b and c. 



