A. G. Tansley. 
'38 
matous mass. In G. dicarpa this internal endodermis comes into 
connexion with the external one during the junction of the leaf- 
trace with the stele of the rhizome (Fig. 37C), thus putting the 
enclosed strand into open communication with the cortical ground- 
tissue. Almost immediately, however, the internal endodermis 
Fig. 36. Gleiclienia dicar pa. T. S. of petiolar strand, per., pericycle ; />//., 
external phloem ; px., protoxylem; int. ph., internal phloem; ph.J., internal 
phloem fibres ; sc., internal sclerenchyma. After Boodle. 
again (Fig. 37B) separates from the external one, and finally dies 
out together with the enclosed fibres. In G circinata the internal 
endodermis, with its enclosed fibres, dies out without making any 
connexion with the cortex (Fig. 38B). In G. Boryi there is no 
sclerenchyma in the concavity of the base of the leaf-trace, but 
the internal phloem, which in G. dicarpa loses itself in the external 
phloem of the stele during the junction, is continued down, as it is 
in G. circinata, into the xylem of the stele for a short distance, 
forming a “ nodal island ” or pocket of phloem which dies out in 
the xylem. 
Turning again to the sub-genus Mertensia we find that the 
leaf-trace of G. linearis, which, as we have seen, has a petiolar 
structure intermediate between that of Eugleichenia and that of the 
typical Mertensias, affects the nodal structure of the rhizome 
considerably more than is the case in Eugleichenia. Though there 
is a good deal of variation in detail, in none of the cases examined 
