48 COMPARATIVE EMBRYOLOGY OF THE RUBIACEAE 
distance backwards toward the archesporial tissue, and is in con- 
nection with the same by means of the micropylar canal. 
The embryo and endosperm present no points of striking differ- 
ence from the same structures already described in other Galzeae. 
Diodia Virginiana 
(PLATE 12, FIGURES 1-12) 
I am indebted to Professor Frank S. Earle for collecting and 
preserving material of this and the following species described. 
NucELLUS. STROPHIOLE AND INTEGUMENT 
From the account already given of the origin in the GaZzeae of 
the nuclei and basal partition, we have seen that the former rise 
independently from the floor of the ovary, and that the latter even 
at maturity of the ovules reaches over to one-fourth the distance 
from the floor to the roof of the ovarial chamber. 
In the forms now to be considered, however, a somewhat dif- 
ferent condition is to be found. Here the basal partition originates 
at the same time with the nucelli, so that in an appropriate longi- 
tudinal section one sees a plate of tissue rising from the floor 
of the ovary, from the sides of which the nucelli, seen as hemi- 
spherical masses, take their origin (fig. 7). With the further de- 
velopment of the ovary, the basal partition and that formed by the 
upper parts of the carpels, grow with equal rapidity, so that at the 
time the embryo-sac is mature the floor and roof moities of the 
ovarial partition fuse at a point half way from the floor to the 
roof of the ovary. At this point, therefore, are inserted the funicles 
of the ovules, whose growth is such as to give rise to the amphi- 
tropous form (figs. 2, 8, and 9). 
Early in the development of the ovule at the time when, in as- 
suming the amphitropous position, its axis is passing through a 
transverse plane, a growth which superficially suggests an integu- 
ment makes its appearance first,on the morphologically lower sides 
of the funicle. Coincident with the origin of this organ which for 
our present purposes we call a strophiole, the single integument 
commences to develop as a ring-shaped fundament about the epi- 
dermal capping cells of the archesporium. The growth of the in- 
tegument is such as to form a long micropylar canal, the mouth 
