990 
Ber ridge , — The Structure of the 
This whorl of twelve or more complex groups of vascular tissue, con- 
stantly appearing in the same position below the ovule, can hardly be 
dismissed as a mere irregularity of the bundle system. It seems not 
improbable that we have here the vestiges of the vascular supply of some 
whorl of organs which was situated between the outermost covering and 
the outer integument of the ovule. 
It seems justifiable to assume that these complexes did at one time 
serve a whorl of organs surrounding the ovule, for although in the process 
of reduction the vascular bundles seem usually to dwindle and disappear 
before the organ itself is lost, as in the case of the perianth of the male 
flower of Ephedra or the abortive ovule of that of W elwitschia , yet these 
complex vascular structures may have survived, as has been suggested by 
Dr. Scott, because they were adapted to the storage of water. Also a very 
clear and somewhat similar case of the presence of vestigial bundles has 
been met with in the oak. In some cross-sections of a young flower the 
stamens were found to be represented by small outgrowths alternating with 
the stigmatic lobes. Just below these minute outgrowths, small branches 
from the vascular bundles supplying the perianth end in little irregular 
masses of reticulately thickened cells. In another flower of about the same 
age, the outgrowths are absent, but the small branch bundles persist. 
The position of these vascular complexes in the base of the female 
flower of Gnetum Gnemon recalls that of ‘ the small complexes of four or 
more bundles ’ which Prof. Pearson describes as supplying the male flowers 
in other species of Gnetum } In both cases they spring from bundles 
which pass on to form the vascular supply of an ovule, and they are situated 
just above the junction of these ovular traces with the traces of the protective 
bracts which in one case form the so-called perianth, in the other the cupule 
of the male inflorescence. If the presence of these vascular structures in 
Gnetum Gnemon is evidence for the existence, originally, of a whorl of male 
flowers surrounding the base of the ovule, the primitive form of the strobilus 
would have been an axis terminated by a female flower and bearing 
a single ring of male flowers, the whole protected by a cupule — the so-called 
perianth. This closely resembles the type of inflorescence suggested by 
Prof. Pearson as possibly the ancestral form ; in his study of the structure 
of the male inflorescence he draws the following conclusion : ‘ Since the 
inflorescence may consist of as few as two flowering nodes and a terminal 
segment (which in some cases is an ovule with appendages) it is conceivable 
that the ancestral type of inflorescence was an axis bearing a single lateral 
ring of male flowers and a terminal female flower/ 
The vascular knots may possibly have supplied a whorl of micro- 
sporophylls rather than complete male flowers ; the female flower of Gnetum 
would then be comparable to the male flower of W elwitschia, and the presence 
1 Ann. of But., vol. xxvi, p. 614. 
