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small cells with lignified walls being present. In the upper parts of 
the leaf, which have a completely developed endodermis, only two 
layers of hypoderma are present and the cells are much larger. 
Above the basal region of the leaf the endodermis consists of a 
sheath of rather large cells somewhat irregular in size. The inner 
tangential walls are mostly of lignocellulose, though here and there 
an unthickened portion of wall occurs which readily dissolves in 
Fig. ii. Abies pectinata D.C. Transverse section through middle portion of 
leaf showing completely developed endodermis. en., endodermis; s., 
suberin; lig., lignocellulose. ( x 240.) 
strong sulphuric acid. These cellulose walls are found chiefly in the 
largest endodermal cells (Fig. 11). The outer tangential walls, with 
one or two exceptions, are lignified and usually have a thin deposit 
of suberin on the inner side. The radial walls, as in all the other 
species described, consist of a central core of lignocellulose bounded 
on either side by a suberised layer; the radial walls are pitted at 
long intervals, the pits being most numerous where they adjoin the 
transverse walls which are unpitted. 
