57o 
Hatfield. — Anatomy of the Seedling and 
traces are eventually differentiated in the basal region (Text-fig. 3, 
L^-L^). These are represented by groups of meristematic cells in which 
one or two vascular elements are to be discerned. 
In a third leaf, no vascular tissue is differentiated at this stage (Text- 
fig. 3, A, Z 3 ). The plumular axis is extremely short ; there are no inter- 
nodes, so that the fusion of the foliage leaves, and of the cotyledons, with 
the stem takes place very nearly at the same level. The leaf-traces 
generally continue their parallel descending course right down to the point 
of junction of the leaf and stem, but this is not always the case ; several 
examples have been observed where the traces on the flanks of the petiole 
run tangentially in the leaf -base itself, as it joins the axis, so tending 
to spread themselves ovit to that side of the axis removed from the middle 
of the leaf. 
B 
G 
A 
Text-fig. 3. a. Transverse section of seedling above stem apex, showing cotyledon tube and 
traces, and first three plumular leaves, in two of which leaf-traces are developed, x 3. B. Transverse 
section of same seedling at point where fusion" of cotyledon tube and of foliage leaves with axis is 
nearly complete, x 3. C. Transverse section of same seedling just above the cotyledonary node, 
x 8. Ci, C 2 = traces of Cotyledons I and II; Zx l -Z x 6 = traces of first plumular leaf; 
= traces of second plumular leaf ; •< — ► marks the intercotyledonary plane. 
In the more typical case described above, there are, just above the 
cotyledonary node, four — or three, by the fusion of two — traces in the base 
of each cotyledon (Text-fig. 3, A), six in the first foliage leaf (Text-fig. 3, A, 
and nine in the second (Text-fig. 3, A, L^-Lp). These all pursue 
a longitudinal and parallel course in the bases of their respective leaves, and 
the condition of affairs at the level where fusion with the axis is just com- 
mencing is shown in Text-fig. 3, A. 
{f) Course of the leaf -traces in the epicotyl. The traces of the first 
foliage leaf now fuse into two bundles (Text-fig. 3, B, Lj), which eventually 
lie at opposite ends of a diagonal, the plane of which is removed by 90° right 
and left from the midrib of the leaf to which they belong, i. e. is parallel to 
the adaxial surface of the leaf. Between the traces of the first and the 
succeeding leaf there occur very irregular horizontally running anastomoses 
— such anastomoses may nearly encircle the stem. The centrally placed 
