212 Sargant and Arber.—The Comparative Morphology of 
The two groups of plumular phloem are extended in strips, each external to 
a xylem plate (VIII, Text-fig. 30). 
At a level very little below the formation of root-plates, the stele of 
the axis is completely masked by the repeated insertion of cauline roots. 
We could not determine in the descending series whether any one of the 
roots, all cut more or less obliquely, represented the primary root. It may 
perhaps never develop at all; its functions being taken over at once by the 
cauline roots. 
A rnomum angustifolium , Sonner. Two seedlings were examined, both 
about the same age. That drawn by Miss Thomas in Text-fig. 31 was cut 
by hand. The bundles of the cotyledonary sheath 
were previously traced by her under the simple 
microscope. From the other she cut a complete 
series of sections, beginning half-way down the 
upper sheath, and ending with the tangled insertions 
of cauline roots at the base of the hypocotyl. 
The cotyledon of Amomum possesses two large 
bundles in its stalk ; one of them runs nearly to the 
top of the upper sheath and then turns downwards, 
while the other hardly enters it. The vascular 
skeleton of stalk and sheath, indeed, is precisely that 
of Elettaria , and might be represented by Diagrams 
I-V, Text-fig. 30, with a few alterations in matters 
of detail. 
The cotyledonary bundles P and P r enter the 
stele of the axis in the same way at the first node. 
The vascular girdle is better developed, perhaps 
Text-fig. 31. Amomum because the seedlings are older than in Elettaria ; 
angustifolium, Sonner. Out- and it seems as if P and P' took an active share 
enlarged. Seedling> sllghtly in its formation by branching to meet the cortical 
traces (PI. X, Fig. 13). At the top of the hypocotyl, 
the formation of a xylem star with double rays is even clearer than in 
Elettaria (PI. X, Fig. 14); but it passes over into the single-rayed form 
more quickly, and this persists longer. The formation of root-plates is 
obscure ; before they are well defined, the stele is lost among cauline 
root-insertions. We could not determine whether the primary root was 
undeveloped, or whether it existed but was hopelessly lost in the series 
among the sections of cauline roots. 
Renealmia racemosa , A. Rich. Two seedlings were cut by Miss 
Thomas from spirit material. The series from the first is fairly complete 
from insertion of stalk downwards, but the xylem is very little lignified. 
