PLATE 50 



Fig. 1. Portion of the base of the pedicel of Nicotiana at a late stage in 

 the process of abscission showing the independent origin of the process in the 

 pith. 



Pig. 2. Portion of the cortex in the separation layer of Nicotiana showing 

 separating cells next to the vascular system. 



[422 1 



