8 THE CoMPARATIVE EMBRYOLOGY OF THE RUBIACEAE 
II. DESCRIPTIVE 
Vaillantia hispida 
Vaillantia is a small genus of the Ga/ieae containing only two 
annual species, indigenous to the Mediterranean region. The plants 
are monoecious; the flowers are borne in threes supported bya 。 
single broadened spiny stalk. Of the three the middle is pistillate, ۰ 
the two lateral staminate. The three-flowered peduncles are in | 
four vertical rows alternate with the four rows of leaves. The 
regularity and perfect radial symmetry of the species studied render 
it easy to section a growing tip so as to cut all the ovules of two 
opposite rows longitudinally. 
The material was obtained at the Botanical Garden at Berlin. 
THE ORIGIN AND DEVELOPMENT OF THE NUCELLUS 
At the period of the development of the pistillate flower when 
the four corolla lobes have met above the hollowed out receptacles 
and overarch the stamens, which are as yet merely rounded knobs 
at the angles of the sinuses of the corolla, four elevations lying in 
the same vertical plane make their appearance near the base of the 
ovary. The outer two of these are ridge like, and by their mode 
of growth meet later in the transverse plane, fuse, extend upwards 
to form the two styles, and downward to form a partition which 
divides the originally unilocular ovary into two chambers. The 
two others are papilliform and lie on either side of the center of the 
floor of the ovary. These are the nucelli. As they develop, the 
partition above referred to passes down between them and separates 
them. Thelower edge of the partition finally fuses with the tissues 
between the funicles of thetwo ovules, making the ovary bilocular. 
We may now turn our attention to the nucellus. For a short 
time its growth is direetly upwards. (Pl. 1. Fig. 1.) There isa 
well marked epidermis, and the cells are quite filled with dense 
cytoplasm and large nuclei. More rapid cell division upon the 
inner side, however, soon causes the apex of the nucellus to be 
directed toward the floor of the ovary. When the bending of the 
ovule is complete, and its definitive condition reached, the micropylar 
