710 Thomas. — Seedling Anatomy of 
the central cylinder, and the halves thus produced pass into the cotyledons 
as the lateral bundles of the petiole. Thus a tetrarch root is formed from 
the 4 doubles ’ and two laterals of the cotyledons. 
It is to be noted that if the 4 double ’ be regarded as one bundle, the 
laterals, coming as they do one from each cotyledon, cannot but be con- 
sidered as two strands, and we have therefore a condition which does not 
fall into either of Van Tieghem’s types, but is partly conformable with 
Type 3, and partly with Type 2. 
Magnolia Sotdangeana (Text-fig. 20) has the same mode of transition 
and general features as M. tripetala , with the exception that the lateral 
bundles do not form a collateral strand just 
below the node, but pass out as two separate 
bundles, one going to each cotyledon as in M. 
tripetala. 
Magnolia acuminata (Text-fig. 21) resembles 
M. Sotdangeana , and forms a tetrarch root in 
a similar manner. Sections from an older seed- 
ling of this species show how completely age 
masks the primary structure. In this individual 
a complete ring of secondary tissues is found 
just below the cotyledonary node, which take 
the place of the obliterated protoxylem groups 
of the ‘ doubles ’ so obvious at an earlier age. 
The transition phenomena of these three 
species are thus precisely similar. 
Magnolia Yulan differs markedly from the 
preceding species in the possession of a diarch 
primary root, and also in the absence of free 
lateral strands in the base of the cotyledons. 
Liriodendron tulipifera (PI. L, Figs. 5-8). The upper part of the 
hypocotyl resembles that of M. tripetala in essential features, but the 
vascular system in the intercotyledonary plane is smaller, so that the stele 
forms a rectangle of which the intercotyledonary sides are shorter than the 
cotyledonary sides. As the intercotyledonary strands pass upwards to 
the cotyledonary node, they unite to form a single collateral strand as in 
M. tripetala , which only bifurcates to form the laterals of the cotyledon 
petioles as the latter diverge from the axis. As the strands of the hypocotyl 
are followed downwards towards the root, the intercotyledonary ones gradu- 
ally disappear, inserting themselves on the more robust cotyledonary strands. 
This leads to the formation of a diarch root. 
Illicium religiosum. This species has not been fully worked out, but it 
would seem to resemble Magnolia Yulan in the absence of lateral bundles 
and formation of a diarch root. 
21 
Text-figs. 20, 21. 20, Mag- 
nolia Soulangeana\ 21, M. acu- 
minata. i nat. size. 
