Evolution of the Angio sperms. 511 
absence of any fossil evidence. The difficulties that beset us here may 
be illustrated by imagining that we wished to restore the flower of the 
Ranales, as typical of Dicotyledons, and that only three genera of the 
Incompletae, such as Casuarina , Populus , and Peperomia , now existed as 
the survivors of the group. 
Further, even if the Gnetales, using the term in a wide sense to 
designate a once numerous, and now almost extinct, group, preceded the 
Angiosperms in point of time, as indeed they may have done, it is impossible 
to derive the Angiosperms from them. For, as we have pointed out, the 
evidence is all in favour of two lines of evolution, which were not identical 
but parallel. From the Hemiangiosperms sprang two distinct lines, the 
primitive Angiosperms ( Ranalian plexus ) and the primitive Gnetales, the 
three highly-evolved living genera of the latter being their sole survivors. 
On our view then these primitive Gnetales did not give rise to the Angio- 
sperms, neither did they continue to be in all essentials Hemiangiosperms. 
Though, as we have pointed out, it is almost impossible to restore these 
primitive Gnetales, from the scanty evidence at our command, we see 
no reason to believe that they did not possess as marked peculiarities 
of their own, as did the primitive Angiosperms. Perhaps the tendency 
to suppression of the megasporophylls, and to reduction in the organs 
of the strobilus, may have even then been at work, though in a less marked 
degree. 
General Conclusions. 
The systematic position of the Gnetales, and especially their relation- 
ship to the Angiosperms, is a question of the greatest difficulty on account 
of the scarcity of the evidence. Three living genera, two of which are 
very highly specialized to particular environments, alone exist, and further 
the group is at present unknown in the fossil state. Yet we are forced 
to the conclusion that the Gnetales are not a modern group, just springing 
into being. Like the Angiosperms, they have had a history in past 
geological periods, though at present we are unable to read the records 
of their former greatness. This is in the main due to the unfortunate 
position of our knowledge of the real nature and affinities of the fossil 
plants occurring in the Cretaceous and Tertiary rocks. 
The three survivals of this ancient group possess fructifications which 
we interpret as reduced pro-anthostrobili. We find that the same, principles 
of evolution, which we have already applied to unravel the tangled skein of 
Angiospermous descent, are equally applicable to the Gnetales. It is thus 
to the credit of the Strobilus Theory, as a working hypothesis, that while 
the Gnetales themselves throw but little light on the ancestry of the Angio- 
sperms — a conclusion which we have consistently maintained — the applica- 
tion of the theory, founded on Angiosperm evidence, to the elucidation 
