founded on the Structure of their Seedlings. 61 
tion in the bundles of the tuber. There are often two or 
three unlignified secondary elements in rows outside them 
(PL VI I, Fig. 3). 
The two protoxylem groups which are flanked by phloem 
shortly die out, and the root is left with a diarch stele 
(PI. VII, Fig. 2). 
The vascular symmetry of Eranthis hiemctlis has already 
been compared with that of Anemarrhena (pp. 4 and 5, and 
Sargant, 35, PI. 2). The resemblance is clear from Diagrams 
VI and X. I will not go over the ground again. But some 
remarks may be offered on the difference between these types. 
The formation of a diarch root-stele in the typical Ranun- 
culaceous seedling is clearly connected with the insertion of 
a vigorous plumular stele on the comparatively insignificant 
cotyledonary traces, and the continuation of both into the 
persistent primary root (cf. Diagram IX). In plumule and 
root alike, secondary thickening is early developed and plays 
an important part. They are connected largely by means 
of secondary xylem, while the primary xylem of the cotyledon 
is continued downwards into that of the primary root. We 
may conceive a remote ancestor of the Ranunculaceae to have 
possessed four cotyledonary traces which regularly formed 
a tetrarch primary root by branching of the xylem according 
to Van Tieghem’s type 1, and that its comparatively slender 
plumular traces were inserted on two opposite traces of the 
hypocotyledonary stele. Then if the plumule began to in- 
crease in importance and develop earlier, its traces would 
exercise an increasing influence on the stele of the hypocotyl. 
The plumular phloem would by degrees unite with the 
adjacent cotyledonary groups, and thus form a single huge 
mass on either side of the stele. The secondary forma- 
tions produced by the action of plumular cambium between 
each mass of phloem and the cotyledonary xylem within it 
would in time arrest the development of the latter, and 
perhaps suppress it altogether. Finally, the root-stele would 
become completely diarch. The vascular systems of Albuca 
(p. 9), Chlorogalum , Anthericum , and Anthropodimn (p. 30) 
