632 Benson and Welsford.— The Morphology of the Ovule and 
With a view to comparing our results among the Amentiferae with 
those from nearly allied forms we selected for investigation species of 
Morus, Ur tic a , and Rheum . 
Morus nigra. 
The ovary here is trimerous or dimerous as in Juglans . It may be 
bilocular with one ovule in each loculus, 1 or bilocular with a single ovule 
(Text-fig. VII. 1), or unilocular also with one ovule (Text-fig. VII. 2). We 
find that in the latter form the ovule is supplied by a strand from each 
carpel (Text-fig. VII. 2, v). The outer integument is supplied with 
vascular strands which bifurcate once before they terminate (Text- 
fig. VII. 1, tf). 
Urtica dioica. 
With the exception of the dimery of the Urtica gynoecium the relation 
of the ovule and carpel in this genus seems to resemble that of Rheum 
undulatum . Hence no separate account will be given. 
Rheum undulatum. 
In this flower we have a very advanced type of the basal orthotropous 
ovule. As is well known the ovary is trimerous and unilocular. 
In a complete microtome series of transverse sections through the 
attachment of the flower we cannot detect any horizontal placental supply. 
This is undoubtedly to be explained by the tapering form of the base of the 
superior ovary. All the area enclosed within the base of the three carpels 
is occupied by the placenta up which runs the lateral bundles contributed 
equally by the three carpels. These relations are shown in Text-fig. VIII. 
1 and 2. As the series of transverse sections is continued upwards the 
concentration of the tracheides increases. We do not think therefore that 
even in Polygonaceae the ovule should be conceived of as axial. 
General Discussion. 
a 
I. Epigyny. 
A consultation of the works of the leading authorities on the morpho- 
logy of the flower shows a general recognition of the difficulty involved in 
the use of term ‘ epigyny ’. 
Asa Gray 2 defines epigynous as ‘ on the ovary or seemingly so ’. 
Pax, 3 after defining the inferior ovary as consisting of axis plus floral 
leaves, continues : — ‘ Freilich wird immer zu untersuchen sein, ob nicht der 
1 Payer, Organog^nie de la fleur. Atlas, Plate 61, Fig. 27. 
3 Asa Gray, Structural Botany, Glossary, p. 409. 
3 Pax, Morphologie der Pflanzen, p. 206. 
