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THE ANCESTORS OF THE ANGIOSPERMS. 
MARY A. JOHNSTONE, B.Sc.; F.L.S. 
At the present time, when the attention of every prominent 
worker in botanical research is turned to the last magnificent 
contribution towards the solution of the problem of the 
phylogeny of the angiosperms, it may not be inappropriate 
to set forth in a journal of special interest to Yorkshire a few 
brief statements concerning the most important recent additions 
to our knowledge of the subject. Condensed within the space 
of a few pages, such a résumé must necessarily be the merest 
outline, and can make no pretentions to attempting a critical 
survey of the various hypotheses which have been formulated, 
much less to add to their number. 
The question involves not one problem, but a whole plexus 
of problems, most important of which may be mentioned the 
following :—the line of evolution along which the typical flower 
and fruit of the angiosperm have progressed; the sudden 
appearance in Lower Cretaceous times of the angiosperm type 
of foliage; which of the modern angiosperms are the more 
primitive—the simple, unisexual, often apetalous forms, or the 
complete, bisporangiate; is the group monophyletic, or have 
monocotyledons been derived from dicotyledons, or vice versa ? 
All recent paleontological evidence tends to confirm the 
view that modern flowering plants are descendants of a long 
line of fern-like, Cycado-filicean, and Cycadean ancestors. As 
this evidence has accumulated, the necessity for continual 
revision and rapid re-adjustment of our principles of classi- 
fication has become more and more apparent. For instance, 
secondary growth can no longer be regarded as a mark of 
Phanerogamic affinity, since it has been shown to be the rule 
amongst the dominant Paleozoic Cryptogams; from amongst 
the Paleozoic ‘Ferns’ many types had to be transferred to a 
new group of Cycado-filices, combining the characters of both 
ferns and cycads, and from these again we get the Pterzdo- 
sperms. These last furnish a strong example of that law of 
evolution which states that the various organs of a plant need 
not necessarily have an ancestral history marked by contem- 
poraneous development. If we take Lygznodendron as a typical 
Pteridosperm we find that it has retained its fern-like foliage 
as well as certain fern-like anatomical characters; that its 
microsporangia or pollen-bearing organs are so fern-like in 
Naturalist, 
