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Transactions. 



There are a few stomata, the guard-cells of which are level with the 

 other epidermal cells and have thickened walls. 



The cortex consists of large, thin-walled, rounded or somewhat irregular 

 cells which have small air-spaces between them and which form a water- 

 storage tissue. In the outermost layers there are a few chloroplasts, which 

 are smaller than those in the leaf. 



Fig. 34. — Gnaphalium Traversii. Transverse section of runner (x 230). 

 a, cells with chloroplasts ; b, colourless cortex ; c, endodermis ; 

 d, pericycle ; e, phloem ; /, xylem ; g, pith. 



The central cylinder is fairly small, occupying less than half the dia- 

 meter of the stem. It is surrounded by a well-marked endodermis in 

 which all the cells are large and have suberized walls. 



