Hill and de Fraine . — On the 
708 
are still contained within the seed-leaves. A triarch root-structure there- 
fore is formed at a very high level of the hypocotyledonary axis. 
A plant with four cotyledons gave rise to a tetrarch root in the same 
manner, although three of the seed-leaf bundles did not start the re- 
arrangement of their vascular tissues until entry into the axis had been 
gained, and, further, the rotation of the xyjem was not nearly so well 
marked as in the plant of this species first considered. 
Another individual with four cotyledons (Series C), afforded further 
evidence of the splitting of these structures. For the sake of clearness 
in description the bundles of these seed-leaves may be termed a , c, and d. 
a underwent bifurcation of the phloem and partial rotation of its xylem 
while still within the seed-leaf, and ultimately gave rise to one pole of the 
triarch root, b performed in a similar fashion, but did not start the re- 
arrangement of the vascular tissues until its entry into the axis ; it also 
formed one pole of the root, c and d followed on the same lines as b , but 
the protoxylem of c died out, its metaxylem effected a junction with the 
metaxylem of d , the isolated phloem-masses fused, so that a triarch root 
resulted. There was thus a transient tetrarch arrangement which became 
reduced to triarch. 
From the behaviour of these bundles it must be concluded that <2 and b 
are derived from two whole cotyledons, and as d gives rise to the remaining 
pole of the triarch root it also may be looked upon as belonging to a whole 
seed-leaf. The remaining strand c plays no important partin the formation 
of the root-structure, and therefore falls into the category of seed-leaves 
which we have termed subsidiary cotyledons . 1 It is to be observed, 
however, that this bundle at first behaved in such a fashion as to lead one 
to suppose that it would form a pole of the root ; for bifurcation of the 
bast and a certain amount of rearrangement of the wood took place. This 
occurrence is not uncommon and is more especially found in species of 
Finns for instance ; the explanation of it may perhaps be left until these 
other examples have come under consideration. 
Cryptomeria japonicci , D. Don. The number of seed-leaves varies 
from two or three, each has two resin ducts situated one at each end of 
the leaf. 
The transition takes place in the same manner as in the plants already 
described, resembling Juniperus virginianum pretty closely. 
All the tricotyledonous plants examined had triarch primary roots. 
Sciadopitys verticillata , Sieb. & Zucc., is constant in its number of seed- 
leaves, never more than two having been observed ; they resemble in 
structure those of Sequoia sempervirens , although there is a larger number 
of transfusion tracheides present ; in fact this tissue is more abundant in this 
plant than in any of the foregoing. 
1 Hill and de Fraine: British Assoc., Section K, York, 1906. 
