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very little: G-Endodermis ; in the latter case the endodermis-cells 

 are either uniform (fig. 2 C), or only those that border on the 

 vascular-bundles of the axial cylinder have thickened walls, while 

 those bordering on the pith between the bundles are thin-walled 

 (fig. 2 B). The walls of the endodermis-cells, at least the thickened 

 ones, become red-coloured when treated with phloroglucin and 

 hydrochloric acid. 



The transverse section of the axial cylinder is nearly always 

 of a more or less oblong shape (fig. 8), the long axis of it, by the 

 species with compressed stem, coinciding with the longest diameter 

 of the transverse section of the stem. The single vascular bundle 

 consists of a phloem, turned outwards, and a xylem, turned in- 

 wards. The xylem is much reduced. In the internodes the vessels 

 are usually obliterated at least in the bigger bundles by which a 

 wider or a narrower channel arises (lg in figg. 2 and 3) bordered 

 with long thin-walled cells. In the nodes, on the contrary, the 

 vessels are preserved. On the innerside of the vascular bundles 

 and on the outer-side, between the phloem and endodermis, you 

 will often find lots of bast. Besides this the axial-cylinder is 

 strengthened by the pith-cells which are very often thickened. 



In many species a circle of separated vascular bundles are 

 lying close inside the endodermis (figg. 3 A — F; 9), the number of 

 them varying considerably in the same species, partly arising from 

 the fact that the leaf-traces are not always passing the same number 

 of internodes before joining the neighbouring bundles. The amal- 

 gamation of the bundles is often on long stretches incomplete, the 

 phloem of the single bundles being plainly separated while the xylem 

 is united. I beg to observe that when two vascular bundles unite, 

 their xylem is first meeting, and the two channels formed by 

 obliteration of the vessels will especially melt into one wide channel 

 while, for some time, the two adjoining parts of phloem will keep 

 separated or at least appear as composed of two. This fact is 

 generally found in one of the two bigger bundles lying before the 

 middle of the two longest sides of the transverse section of the 

 axial cylinder. In many species this bundle is composed of three 

 and in such species, as a rule, the three separated parts of phloem 

 are forming a circle round a joint channel (fig. 3 A, i>, C). In a 

 few species the three bundles named are generally quite separate 

 and each of them having its own channel (fig. 3 jB); in such cases 

 the two of the bundles are lying freely in the pith while the third 



