founded on the Structure of their Seedlings. 51 
symmetry is probably due to mechanical causes. The seed 
is connected with the main axis by the long slender petiole 
of the cotyledon, and this enters the rather complicated 
cotyledonary sheath at an acute angle. The two bundles are 
so placed as to give strength and elasticity to the junction. 
In all three species there is a fairly long hypocotyl ; that 
is, the plumular traces join those from the cotyledon some 
distance above the level at which the stele becomes completely 
root-like. The cotyledonary traces are placed opposite each 
other in the sheath just above the first node, and in this 
region they seem perfectly equivalent. 
The traces of the cotyledon enter the hypocotyledonary 
stele from opposite sides, and are separated by two plumular 
traces. The other bundles of the plumule are inserted on one 
or other of these four traces at the first node. 
The fourfold stele below the first node has a very character- 
istic appearance. Each of the four xylem* masses is crescent- 
shaped, and each group of phloem is placed in the concavity 
of a crescent. As the eight horns of the xylem crescents 
reach the pericycle and form four pairs of xylem rays 
alternating with four phloem groups, we seem at first to be 
looking at a tetrarch root. Closer inspection shows that the 
centre of the stele is occupied by a single group of protoxylem 
formed by the union of four internal groups. From this 
centre radiate four narrow rays of parenchymatous tissue 
dividing the four xylem crescents from each other. 
Before the protoxylem becomes external a number of 
cauline roots are given off from the stele almost simultaneously. 
There are commonly four of these, and each is placed opposite 
one of the parenchymatous rays. 
The primary root is tetrarch in Renealmia racemosa and 
Elettaria cardamomum. In the only complete series cut from 
Amonium angustifolium the central stele vanishes after giving 
off four cauline roots simultaneously. There would seem 
to be no primary root at all. This may be an individual 
peculiarity, or the primary root may be present but inclined 
at such an angle as to be mistaken for a cauline root. 
E 3 
