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The epidermis of the lower surface (Fig. 16 C; Fig. IH B 

 and /)), along the margin of the leaf, is almost exactly like 

 that of the upper; the stomata are absent from a broad band 

 along the middle, where the cells are elongated and narrow. 



The differentiation of the mesophyll is fairly distinct. The 

 palisade-cells, towards the apex of the leaf, are obliquely placed. 



Fig. 17. Saxifraga aizoides. 



The leaf: A, Transverse section. B, Longitudinal section. C, Spongy parenchyma. 



(A, B, C s'Vi). 



