512 
Arber and Parkin. - Studies on the 
of the Gnetales, does furnish us with a logical argument to account for the 
very existence of these plants at the present time. 
Of the three genera, W elwitschia appears to us to be~the most primi- 
tive as regards its fructification. We have shown that the male strobilus 
of this plant is, in its essential features, an amphisporangiate Pro-antho- 
strobilus. It possesses a perianth, and both male and female organs, the 
latter occupying the apical portion of the strobilus. The female fructifi- 
cation of the same plant, and both the male and female fructifications of 
Ephedra and Gnetum , we regard as pro-anthostrobili reduced to the mono- 
sporangiate condition, each possessing organs homologous with those of 
the amphisporangiate male strobilus of W elwitschia. 
The reduced strobili of the Gnetales are grouped in dense aggregates 
or clusters, which in the case of Ephedra and W elwitschia find a close 
parallel among the Amentiferae. The parallelism with Populns , especially 
with the amphisporangiate species Populus glauca , Haines, is very striking. 
These two genera might almost be spoken of as the Amentiferae of the 
Gnetales. 
We regard the Gnetales as a race of Gymnosperms, nearly related to 
the Angiosperms. There are many and varied indications that both groups 
have sprung from a common stock, and that their lines of development 
have, in many respects, continued parallel. The common ancestors of the 
Angiosperms and Gnetales are the Hemiangiosperms, a race as yet 
hypothetical. 
The following table expresses the relationships of the Gnetales to 
those groups to which, on our view, they are most nearly related. 
