310 MR. A. S. HORNE ON THE STRUCTURE AND 
4, VASCULAR STRUCTURE OF THE OVARY. 
The vascular supply to the hermaphrodite flower emerges from the torus into the 
obsolete pedicel as a single complete cylinder of closely adjacent bundles, which 
segregate at the base of the flower into three concentric cylinders :—(1) an outer 
peripheral cylinder; (2) an inner peripheral cylinder; (3) a radial or septal cylinder 
consisting of fine strands (text-figure, p. 311). 
The inner peripheral cylinder expands in the body of the ovary and surrounds the 
loeuli. The bundles of the cylinder branch and anastomose among themselves. In the 
superior part of the ovary the vascular structure becomes angular, owing to the presence 
of bundles from the outer cylinder which take up a position behind the loculi. This 
structure tapers towards the style, the smaller bundles collecting at the seven angles (in 
heptamerous ovaries) about the bundles which are connected with the outer cylinder, 
aud, finally, seven arc-shaped bundles are left which extend into and occupy a *' dorsal” 
position in the stylar lobes. In transverse sections through the superior portion of the 
ovary the outline of the inner vascular system is polygonal. The behaviour of the septal 
bundles is not easy to follow. In the inferior portion of the ovary they split into a 
number of fine, thread-like strands whose xylem up to the time of fertilization is un- 
differentiated. These strands diverge upward, forming three small groups in each septum. 
The strands of the outer group extend towards the inner peripheral ring, but some die 
out. Two little groups extend inwards and are concerned in feeding ovules on either 
side—the single ovule of each loculus being fed by strands from the two adjacent septa. 
The later history of these strands is masked by post-fertilization changes leading up to 
a general sclerosis of this region, which ultimately becomes the excessively hard endocarp. 
The strands of the outer peripheral cylinder correspond fairly accurately in number to 
the staminal bundles, and the greater number pursue an independent upward course in 
the body of the ovary as far as the point of insertion of the stamens. Some of the 
bundles branch during their course, giving off a bundle which joins the inner cylinder 
in the superior portion of the ovary in the manner described above. At first this 
behaviour was thought to be an occasional irregularity, but the examination of a number 
of ovaries in serial section showed conclusively that it was of greater significauce. It 
was found that the bundles behaving in this way tended to be equal in number to the 
loculi. In all cases the bundles in question formed the angles of the upper portion of 
the inner vascular system (** dorsal ” position). In a heptamerous ovary, seven bundles 
were found behaving irregularly. Six of these were composite in character. The stamens 
associated with them emerged opposite the loculi, so that they may be regarded as 
forming a definite whorl. Diagrams made from serial sections of this particular ovary 
are shown in the text-figure on p. 311. Diagram 1 shows the cylinder of vascular 
tissue in section as it appears in the torus immediately below the pedicel. The small dots 
represent staminal bundles which occur in groups. In diagram 2 the pedicel is free 
from the torus and the vascular tissue has branched, forming three concentric cy linders. 
In the following diagrams the bundles of the outer vascular cylinder are represented by 
large dots, the bundles of the inner cylinder by smaller ones, and the septal strands by very 
