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core of lignocellulose with a suberised layer on either side. The 
former are delicately pitted. A considerable number of lignified peri- 
cyclic cells are found, a few of these having quite thick walls and 
resembling the cells with cellulose walls found in the pericycle of 
Larix. A further resemblance to Larix is seen in the presence of a 
single layer of lignified hypodermal tissue. 
Fig. 12. Tsuga canadensis Carr. Transverse section of leaf showing the endo- 
dermis interrupted by the single large resin canal. Both inner and outer 
tangential walls largely unlignified. Radial walls lignified and suberised. 
en„ endodermis; lig., lignocellulose; s„ subcrin. (x 240.) 
Though the walls of the endodermis are so thin, they are all 
thickened and this leaf seems to be more xeromorphic in character 
both as regards the endodermis and pericycle than is that of Larix. 
General Conclusions 
Eleven species of the Abietineae were examined and in all of these 
an endodermis was found to be present which consisted of rather 
