179 
the Young Epicotyl in some Ranalean Forms. 
usually differentiated in seedlings of the other genera. Its appearance in those 
of Ranunculus, Trollius, &c. may be part of the precocity which is observed 
in the secondary thickening. This seems to be borne out by the fact that 
endodermis is present round the individual strands in the adult plant, not 
only in Ranunculus where an internal sheath is found in the seedling, but 
also in other plants, for instance P odophyllum, in which the seedling is quite 
normal. The origin and function of the endodermis has been reconsidered 
of late years by various writers, for instance by Professor Lang in his recent 
paper on the Ophioglossaceae, 1 and it seems possible that its phylogenetic 
importance in the present instance has been over-estimated, especially in 
view of the specialized geophytic and aquatic habit of the species in which it 
is found, whereas it is absent in the more normal R. arvensis . The order 
Nymphaeaceae, the other instance of the appearance of an internal endo- 
dermis, cited by Professor Jeffrey for the Ranales, is also of aquatic habit, 
and the presence of an extra endodermis in the stem of water-plants is not 
an unusual phenomenon (e.g. it is found round the cortical leaf-trace 
bundles in Menyanthes). 
To sum up the results of this investigation, there are two centres of 
special phylogenetic interest : 
i. The Leaf-trace Insertion. There is a general prevalence of the 
trilacunar trace in the seedlings of Ranales. This strongly supports 
Mr. Sinnott’s conclusions, based on a study of the adult plants of the cohort. 
I 2. The Type of Vascular Cylinder. A single ring of bundles connected 
at a very early age by cambium is found almost universally throughout the 
seedlings of the cohort. This single ring of bundles does not appear to be 
a mere embryonic character, as suggested by Mr. Worsdell, 2 for such forms 
as do not exhibit specialized morphology due to a geophytic habit show 
a similar structure throughout life (e.g. Helleborus foetidus and Magnolia ). 
Interfascicular cambium is usually absent in the adult stems of the herba- 
ceous Ranunculaceae, but it is invariably present at some stage in the 
seedling. 
The siphonostelic appearance described by Professor Jeffrey in 
Ranunculus and Anemone is shown to occur also in Caltha and Trollius . 
Evidence is brought forward in favour of its wholly secondary origin. 
In conclusion I should like to acknowledge with gratitude my deep 
indebtedness to Dr. Thomas for her constant advice and helpful criticism 
throughout the progress of this investigation. 
Bedford College. 
1 Lang, W. H. : On the Anatomy and Branching of the Rhizome of Helminthostachys zeylanica. 
Ann. of Bot., vol. xxix, 1915, p. 35. 
2 Loc. cit., p. 654. 
