
1901} ERIOCAULON DECANGULARE 33 
leaves of the genera which he examined, and, in accordance 
with his opinion, the outer sheath would represent true paren- 
chyma, the inner sclerenchyma. He saw, however, that the 
so-called sclerenchyma does not show the same development in 
all the bundles, but he makes no allusion to its possible identity 
with a mestome sheath. - The outer sheath is only described as 
being composed of thin walled cells ‘‘stretched longitudinally,” 
which does not seem to indicate that a true parenchyma sheath 
was observed. The testing of these sheaths with sulfuric acid 
seems to have been omitted. 
The mestome bundles of the leaf are almost parallel from 
the base to near the apex, where they unite and form an appar- 
ently single bundle. When viewed superficially the nerves 
might appear without anastomoses, since the numerous dia- 
phragms filled with chlorophyll make the inner portion of the 
leaf very indistinct. When the blade is divided into halves the 
anastomoses may be seen, not at all infrequent, connecting the 
larger nerves at more or less acute angles. In this way anasto- 
moses become plainly visible even without any further treatment 
with potassium hydrate, and they are often seen in transverse 
sections. It seems very surprising that Poulsen did not notice 
_ them in any of the fifteen species which he examined, and that 
he points out the absence of anastomoses as one of the principal 
characteristics of the order. It may be that they are not devel- 
oped in any of these fifteen species, but they are certainly very 
plainly visible in £. decangulare, and I have found them also in 
E. gnaphalodes and in Lachnocaulon Michauxii. 
The structure of the main nerves is very uniform. None of 
the mestome bundles near the middle of the blade are of any 
considerable size when compared with others, and it might be said 
that the leaf has no midrib. It has already been stated that 
some of the nerves are smaller than others, and that a corres- 
ponding variation in regard to the development of the inner 
sheath is noticeable. However, the hadrome and leptome are 
common to all the main nerves, but are naturally larger in the 
thicker mestome bundles than in the thinner. The leptome 
