164 BOTANICAL GAZETTE [SEPTEMBER 
rated bundles which are at first collateral, but soon become amphi- 
vasal. Fig.-1 shows this region of the stele. Not until a consider- 
ably older stage is reached do certain bundles turn inward and run 
for a distance in the medulla before turning out to the leaves. Fig. 2 
shows part of a section through the mature rhizome; most of the 
bundles are amphivasal, and some of them run in the medulla; g isa 
gap through which a medullary bundle has lately passed, and it will 
be noticed that the endodermis curves inward around the edges of 
the gap for a short distance, thus making the cortical parenchyma 
continuous with that of the medulla. This intercommunication of 
cortex with medulla is even better marked in the base of the flowering 
axis, as is shown in fig. 3. It will be seen that the endodermis extends 
around the edges of the gaps for a short distance, and completely 
encircles one small section of the vascular ring. It seems reasonable 
to believe that if the gaps in the central cylinder of the seedling of 
Acorus were not so narrow the cortex might communicate with the 
pith as it does in the seedlings of other Araceae possessing a wider 
central cylinder. 
ANTHURIUM ACAULE.—In the hypocotyl the central cylinder is a 
hollow tube consisting of xylem, phloem, pith, and surrounded by an 
endodermis. Just below exit of the single cotyledonary trace the 
vascular ring breaks up into a circular row of five or six collateral 
bundles or meristeles. Above the exit of the cotyledonary tract the 
row is horseshoe-shaped, but soon becomes circular again owing to 
the reunion of the bundles on the two sides of the cotyledonary gap- 
The endodermis cannot be followed clearly owing to its poor develop- 
ment. The stele retains its form of a ring of about six collateral 
bundles through the first internode. At the upper end of the inter- 
node several bundles divide, and certain of these turn outward 
traces of the second leaf, while others turn inward and run upward 
through the pith, becoming traces of leaves higher up. In the young 
stem no concentric strands have been found. 
Monsteroideae.—Monsrera pELIcIosa.—The hypocotyledonary 
Stele consists of a circle of collateral bundles inclosing a parenchyma 
tous medulla. Nearly a third of these bundles bend outward at se 
side to supply the cotyledon; a little above this point bundles begin = 
to run in the medulla; in other words, the central cylinder early 
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