the Genus Hottonia . 
261 
entered the main stele (dr. 1). After the fusion of a trace either with the 
main or lateral steles, the adaxial xylem, phloem, and endodermis may 
persist for a short distance down the stem, thus forming little pith strands 
with reversed orientation (PI. XX, Fig. 3, and Diag. 4, p. 2 56). 
If the tendency towards concentric structure were carried somewhat 
further, and the size of the main stele relative to that of the branches were 
br 3 
Text-fig. 5. a. Diagrammatic transverse section across the base of the inflorescence of 
H.inflata. (x 20.) b. The same at lower level, (x 5.) br. 1-5 = successive branches ; m.st. == 
main stele ; rts. = roots ; ste. = part of branch 3 incurving to form a complete stele. 
reduced, we should have Jeffrey’s amphiphloic siphonostele, as it is we have 
this suggested (Diag. 4, p. 2 56). These internal strands very soon die out, 
and there is apparently no trace of the lignified ring and core of H. palustris . 
In both species the leaf anatomy is very simple ; the mid-rib is traversed 
by a single collateral vascular bundle, which has a tendency to become 
more or less concentric in its passage through the cortex of the stem. A 
