673 
certain Orders of the Ranales . 
that of the leaf of Paeonia and of M agnoliacecte ; with the former through 
the two distinct traces of the primitive cylinder in the lower and upper 
parts of the petiole respectively. In some genera the same formation 
of concentric bundles occurs, as in Paeonia and Berheridopsis , and these may 
almost certainly be interpreted in the same way as in those genera. The 
presence of what are undoubted representatives of medullary bundles in the 
leaf of Cananga are a perfect replica of the structure in the leaf of some 
species of Magnolia ; as in the latter, the vascular structure of the leaf 
of Cananga has taken a half-way stride, as it were, towards ceasing to 
repeat the phylogenetic character of genuine typical medullary bundles, 
i. e. at each evolutionary stage the medullary bundles are being set back 
more and more from the pith into the rank of dorsal arc-bundles, and in the 
structure of the present-day Cananga , as in the Magnolias, we see a transi- 
tional stage represented. The other primitive character, viz. the cylindric 
structure, seems to have disappeared from the leaf of this plant. 
Bibliography. 
Guillard : Singuliere composition de la nervure dorsale dans le- Cananga. Adansonia, vol. ix, 
1868-70. 
BERBERIDACEAE. 
The primitive floral parts of this order find their counterpart in the 
vascular anatomy which, in my opinion, is also markedly primitive. 
I will first consider one of the herbaceous members of the order, 
viz. : — 
Podophyllum peltatum y L. 
This is one of the best examples in the vegetable kingdom of a plant- 
organization in which the leaf appears to be the most important and 
all-dominating vegetative organ of the plant ; in this case, at any rate, the 
stem is entirely subordinate to the leaf and the vascular structure of the 
latter clearly gives origin to that of the former. 
FI. stem \ Of the 3-4 ranks or rings of bundles here present, 
the outer one-to-two series are entirely foliar and pass out into the two 
large leaves. The second ring from the centre splits, its bundles each 
dividing and sending each a branch into the leaf of that side ; there are thus 
left two ranks or irregular rings of bundles, an inner one of large, an outer 
of smaller bundles which are continuous up into the peduncle, and are 
doubtless used up in supplying the floral foliar organs (Fig. 41). 
Diphylleia cymosa, Michx., has practically the same structure as the last 
plant ; in the peduncle is an external rim of sclerenchyma with the smallest 
bundles attached to it. 
