In the thicker ones such as Pittosporum (fig. 6), the double upper 
epidermis seems to curve outward rather than inward, but prob- 
ably most of the thinner leaves would show incurved epidermal 
margins. The combination of collapsed mesophyll cells and 
infolded epidermis thus partly protects the raw edge until by 
modification and mitosis cells are established which can provide 
the permanet recortication. 
The cicatrice is usually clearly differentiated even in unstained 
free-hand sections. This is due in part to the modification of 
its walls, which are often brownish, and in part to the death of 
cells with consequent loss of contents. With reagents and stains 
