497 
Evolution of the A ngio sperms. 
If we institute a comparison between the fructifications of the three 
genera of the Gnetales, we arrive at the following conclusions, each of 
which merits separate consideration. 
1. One fructification is amphisporangiate, the others are all mono- 
sporangiate. 
2. Each fructification, in addition to microsporangia or a megasporan- 
gium, contains other organs, which we, with others, regard as constituting 
a perianth. 
3. The fructifications are grouped in dense, sometimes complicated, 
aggregates. 
4. The microsporophylls and microsporangia bear some likeness to 
Angiospermous stamens, but at the same time the differences are no less 
marked. 
5. There is no trace of a megasporophyll, comparable to a carpel. 
The female organ is a solitary terminal megasporangium, with one or two 
integuments. 
The Amphisporangiate Condition Primitive. 
The amphisporangiate condition is undoubtedly present in the male 
fructification of Welwitschia , though the megasporangium is no longer 
sexually functional. Hooker, himself, was much impressed by his dis- 
covery of the functionless ovule in this fructification, which he considered 
gave great weight to the view that the Gnetaceae had arisen from 4 herma- 
phrodite-flowered plants , . 1 
Coulter and Chamberlain remark that c while the flowers are functionally 
monosporangiate, there is evidence of their derivation from a bisporangiate 
condition ’. The same authors add that ‘ the whole structure is puzzling 
and anomalous among Gymnosperms, for it seems to indicate derivation 
from a perfect flower ’. 2 
The male fructification of Welwitschia , in our opinion, is the key to the 
floral ’ morphology of the Gnetales. We regard it as a strobilus, possess- 
ing all the peculiarities of that particular type, which in our earlier paper 
we termed an Antho strobilus. The anthostrobilus 3 was defined as an axis 
bearing perianth members, microsporophylls and megasporophylls, arranged 
in a characteristic order, the female organs being invariably placed above the 
microsporophylls. One variety of the Anthostrobilus, in which the ovules 
alone perform the task of pollen-collection, was distinguished as a Pro- 
anthostrobilus. The strobilus of the Bennettiteae is an example of a 
pro-anthostrobilus. On the other hand, the Eu-an thostrobilus or Flower 
(the latter term being used only in a rigidly restricted sense) is typical 
2 Coulter and Chamberlain (’01), p. 120. 
Arber and Parkin (’07), p. 37. 
1 Hooker (’63), p. 24. 
