82 
Transactions of the Royal Society of South Africa. 
does not appear to involve the conclusion that the " perianth " in the one 
group is phylogenetically related to that of the other. * 
(2) There is no evidence to show that the innermost envelope is phylo- 
genetically related either to the ovary or to the integument of the Angio- 
sperm. It probably consists of a modified leaf pair homologous with the 
cupule. 
(3) The nucellus is the direct prolongation of the axis which bears the 
envelopes. 
(4) The axis of the flower is homologous with the axis of the spike. 
(5) The " spike " and the female flower are modifications of the same 
primitive structure, the character of which is certainly not indicated by any 
evidence at present available. An obvious suggestion is that it consisted 
of (1) a terminal nucellus surrounded by a single ovular envelope; (2) a 
ring of lateral male flowers, below which stood (3) one or more modified leaf 
pairs. 
A comparison of the Gnetum female flower with those of the other 
genera and with the male flowers of Welwitschia will certainly lead to the 
conclusion that the ovule {i.e. nucellus + envelope I, vide Plate XVIII) is 
strictly homologous throughout the group. 
The view that the second envelope of the Welwitschia female flower is 
the equivalent of the whorl of microsporophylls of the male flower is not 
disproved. On the other hand, there is no convincing evidence in its favour. 
The same is true for the alternate hypothesis, which neverthless most 
morphologists will probably prefer, viz. that this envelope (II, Plate XVIII) 
in Welwitschia and Ephedra is homologous with II (and therefore with III) 
of the G-netum flower. The comparison may probably be extended to the 
two whorls of " perianth " in the male flower of Welwitschia. 
If these generalisations represent an approximation to the truth, we 
must accept the conclusion that these four flowers are modifications of a 
common primitive type— a conclusion which has never been seriously ques- 
tioned. Hitherto the only direct evidence for the former existence of such 
a common type has been the present existence of the male flower of 
Welwitschia — ^presumed to be a reduced condition of a primitively herm- 
aphrodite flower. To this we may now add the new knowledge furnished by 
MM. Lignier and Tison for Gnetum. 
A fuactionally hermaphrodite spike occurs not uncommonly in Gnetum f 
as well as in Ephedra. J The new light now thrown upon the relation 
b3fcw33n the flower and the spike in Gnetum compels us to consider whether 
it does not also provide a new basis for the comparison of the flowers and in- 
florescences of the group and for tracing their descent from a common type. 
* Of. Coulter and Chamberlain, 1910 ; Lignier and Tison, 1012, p. 125. 
t Pearson, 1915, B and C. 
t Wettstein, 1907 ; Porsch, 1910. 
