386 
H. F. Wernham. 
we speak of this type as being relatively primitive. We have been 
led, moreover, to the conclusion that all the Sympetalae lie upon 
this portion of the evolutionary tree. 
But many of the Archichlamydeae may not be referable to this 
portion. The biological tendencies which have been described in 
these chapters have in all probability operated in varying combi¬ 
nations, revealing themselves in many different ways ; other ten¬ 
dencies may have come into play, though such are necessarily limited 
in number ; the same biological advantage may be secured in more 
ways than one, as we have seen in the course of our studies. The 
net result has been that several lines of descent may have diverged 
from any particular stock D. Some of these lines may have per¬ 
sisted, the product of their determining tendencies being reflected 
in various groups, existing or extinct. Those which like DR 
persisted beyond the appearance of the Dicotyledons ( i.e ., above the 
surface Y,—Dd 1? Dd 2 .... in the diagram) have, we suppose, in some 
cases at least, produced branch-systems of their own. It is upon 
one or more of such systems that many of the known Archichlamydeae 
doubtless lie ; and far from being of necessity a single indivisible 
group, as the views of more than one modern systematist would 
seem to imply, the Archichlamydeae must be separated into as many 
groups 1 as there are branch-systems of descent corresponding to the 
lines Ddj, Dd 2 ... in the figure. The Archichlamydeae are no less 
likely to be polyphyletic than are the Sympetalae. 
Engler’s system has been justly applauded for its recognition 
of certain affinities which that of Bentham and Hooker does not 
express 2 on account of their maintenance of the group Incompletae. 
But our approbation of the German system should not extend to 
its total abolition of this last-named group. Its superiority over the 
English system would have been indisputable indeed, had it 
banished the Sympetalae and associated the component families 
of this series with their respective archichlamydeous predecessors 
in descent—Primulales with Centrospermae, Ebenales and 
Cucurbitaceae with Parietales, and so on. The group Incompletae 
as it stands might indeed have been reduced in bulk ; places might 
be found for many of them among the progeny of the ranalian 
ancestor. 
This supposed done, and all the dicotyledonous cross-affinities 
determined, would there remain no Archichlamydeae whose con- 
1 The Centrospermae may come under this head. 
2 Notably the affinity of Caryophyllaceae and their allies with 
the Curvembryeae (Centrospermae). 
