47 2 
Notes. 
ring. At a lower level, the bast-circle divides, opposite the cotyledon bundles, into 
two well-defined masses. During this rearrangement the xylem groups come into 
contact, the metaxylem derived from the seed-leaves joins up with the plumular xylem, 
and thus the protoxylem becomes isolated. The subsequent changes are essentially 
the same as those described for Taxus. 
Cupressus pisifera , C. Lawsoniana , and Thuja orientalis all have two cotyledons, 
each with a single collateral vascular bundle. The transition phenomena are of the 
same type as in Taxus , and result in the formation of a diarch root. 
Libocedrus decurrens , also, is similar, but the number of seed-leaves is three, and 
the primary root is triarch. 
Cedrus Deodar a. — There are usually eleven or twelve cotyledons; the number, 
however, varies. Each contains a single collateral endarch bundle throughout its 
whole length. 
Above the cotyledonary node the seed-leaves fuse to form a well-defined tube, 
the inner surface of which is corrugated ; each ridge corresponds to a cotyledon, the 
foliage leaves of the first node fit into the furrows, and, before the axis is reached, 
these leaves fuse with the cotyledonary tube. Fusion with the axis takes place, and 
the general appearance of a transverse section, taken immediately below the cotyle- 
donary node, is that of a monocotyledonous stem. This appearance is, of course, 
due to the disposition of the leaf-traces of the first three or four nodes ; these bundles, 
however, speedily lose their identity, and, a little later, so also do the vascular strands 
of the first node. The bundles of the cotyledons now become placed closely together, 
so that the limits of any one is difficult to determine. At a lower level a gradual 
change occurs ; the phloem groups fuse together in pairs, and, at the same time, the 
masses of xylem undergo rotation in such a manner that two neighbouring protoxylems 
become exarch, fuse, and occupy positions alternating with those taken up by the 
phloem groups. Thus a typical root is formed, usually pentarch or tetrarch. 
Abies Firma , Actinostrobus , Callitris , Larix, and some species of Pinus, are, on 
the whole, of the same type. 
Pinus Mur ray ana var. Sar genii. — Four cotyledons are usually present : each 
contains a single bundle which has transfusion tracheids adjoining. 
Near the base of the cotyledons the phloem of the bundles bifurcates, and the 
xylem rotates in such a manner that the protoxylem becomes situated between the 
two groups of phloem elements. In this condition they enter the axis, and in their 
passage towards the centre the rearrangement becomes more marked. During the 
downward course the eight phloem groups fuse in pairs, the metaxylem takes up 
a position internal to the phloem, and, as the protoxylem is already exarch, a tetrarch 
root is formed. 
There is, however, some variation. Thus another seedling also had four coty- 
ledons, the bundles of three of which exhibited the rearrangement described above 
while still in the leaf, while the fourth remained undivided throughout its whole 
course. The central region of the axis being reached, the fourth cotyledonary bundle 
played the part of a plumular trace, and fused up with the two epicotyledonary 
bundles situated upon its flanks. The other three seed-leaf strands behaved in the 
manner already indicated above. Their phloem groups joined with the adjacent bast 
