“3 < 32 Dy copenge ne eenenetnneatee 
1907] HOLM—RUBIACEAE 169 
containing raphides occur in the cortex proper. The pericambium 
is thin-walled and continuous. Secondary formations take place at an 
early stage of these roots and thus the primary structure is obscured; 
the leptome occurs as several broad strands outside a much broader 
zone of hadrome, with many rows of vessels and thick-walled con- 
junctive tissue. 
While studying the roots I noticed the peculiar fact that in some 
of these the lateral branches did not penetrate the cortex at once, 
but remained enclosed for some distance, thus traversing the cortical 
parenchyma although fully developed. The structure of these, how- 
ever, was normal and they were developed from the pericambium. 
Such cases were merely exceptional, however, but may nevertheless 
deserve mention. Similar structures have been recorded for Car- 
pocephalus and Eriocaulon.7 
The stem.—An internode from a long, vegetative shoot of the 
previous year is cylindric, though somewhat flattened on account of 
its horizontal direction of growth, and it is very smooth. The cuticle 
is wrinkled, and the epidermis is quite thick-walled; hairs and stomata 
occur, but they are not frequent. Tannin was observed in the epi- 
dermis, also in the peripheral strata of the cortex, which is thin-walled 
and compact, contains raphides, and occupies the greater portion of 
the cross-section. A thin-walled endodermis, with the Casparyan 
spots plainly visible, surrounds the central cylinder. In the outer- 
most stratum of this, thus bordering directly on the endodermis, I 
noticed about four very thick-walled cells, which resembled stereome 
but which proved to be secretory cells like those recorded by SOLERE- 
DER as characteristic of Mussaenda, Isertia, Cinchona, and a few 
other genera; they are quite long and very thick-walled. The stele 
consists of many leptome strands and broad rows of vessels with nar- 
row (one single row) medullary rays, while the center is occupied 
by a thick-walled, solid pith. 
In shoots of this year’s growth the structure is the same, but cells 
containing raphides are more abundant, and the stele shows its 
primary structure more distinctly, with the leptome and hadrome 
arranged in two large groups on the sides of the flattened internodes. 
The erect shoots are strictly cylindric in outline, but show the 
7 Hom, T., Eriocaulon decangulare L. Bot. GAZETTE 31:20. Ig0I. 
