\ 
the Young Epicotyl in some Ranalean Forms. 171 
the six phloem groups are quite distinct. The elements are much less 
compactly arranged than in the other species. 
R. hederaceus . The internodal strands may be two, three, or six in 
number. At the node there is a ring-like joining-up showing secondary 
thickening, but the individual strands can still be distinguished although 
a distinct internal and external endodermis is present. 
R. aquatilis and R. Flammula are similar. The internal endodermis 
is the more marked, though both are present at the node. 
4. R. Ficaria . The apparently single-lobed cotyledon seems to be 
directly continued into the main root. The tuber is really the first lateral 
root, and arises later. The first foliage leaf appears to arise at its 
apex and forces its way through the base of the cotyle- 
donary petiole. A second lateral root is formed at 
almost the same level, but does not store food (see 
Text-fig. 37). The anatomy is somewhat special and 
needs further investigation. The composition of the 
plumular strand is difficult to elucidate. It is brought 
into contact with the cotyledonary system at the node, 
but immediately below the lateral appears again as an 
independent unit continuous with the vascular axis of 
the tuberous root, whereas the cotyledonary strand forms 
the diarch root stele. 
Professor Jeffrey 1 examined a number of species 
belonging to the type which I have called group 3, of 
which R. acris has also been fully described by him. His 
material was apparently somewhat older than the majority 
of the seedlings examined in this investigation. 
He interpreted the structure found as a siphonostele 
with leaf gaps through which the internal and external Ranunculus 10 ' 
phloeotermal layers are connected, and from this tubular curia. Nat. size, 
stele he considers that the ring of bundles has been derived 
by overlapping and lengthening of the leaf gaps and loss of endodermis. 
Professor Jeffrey, in company with other anatomists, seems to have 
used terms, such as siphonostele, describing vascular structure as applying 
to primary tissues only. Whatever may be the significance of the endo- 
dermis, it has been shown that the tubular appearance of the vascular 
system in the genus Ranunculus is due to secondary tissue, and hence the 
term siphonostele, as now used, cannot be correctly applied to the structure. 
The differences between the vascular structure of Ranunculus seedlings 
and more typical forms, irrespective of the question of endodermis, are as 
follows : 
1. The secondary wood elements are irregularly intermingled with 
1 Loc. cit., p. 617. 
