5^2 
Holden and Bexon.—On the Seedling 
The simplest type, {a\ which is relatively rare, is that shown in 
Figs. 36- 9, in which the adaxial bar divides into two bundles, each of which 
rotates and unites directly with the midrib. An advance, (b), on this type 
Pigs. 36-42. Camera lucida outlines of successively lower sections through the young plumular 
bud, showing the simplest type of bundle fusions occurring at the bnse of the petiole (Figs. 36-40) 
and the passage into the epicotyl of the three bundles from each leaf, x 20. 
Figs. 43-9. Transverse sections through a petiole in which a slightly more complex type 
of fusion of the adaxial bundles with the abaxial constituents occurs. Figs. 44-9 are from the petiole 
which is fellow to that shown in Fig. 43, the adaxial bundle on the right behaving similarly, whilst 
that on the left shows a still further complexity. (Camera lucida outlines x 20.) 
is shown by those petioles in which each of the two bundles derived from 
the adaxial bar rotates and unites with a small lateral strand adjacent to the 
midrib, the compound strand thus formed then uniting with the midrib 
(Fig. 43). A still further advance, (c) y is illustrated by the division of each 
of the two original bundles derived from the adaxial bar (Figs. 54,55). Of 
