86 
Margaret Benson 
He thinks there is strong negative evidence against the view that 
a sporophyll of the megaphyllous type had been originally present 
and has been lost but he concludes that the meagre positive evidence 
at present available is distinctly in favour of a common megaphyl¬ 
lous (meriphyllous) origin for the Cordaitales and Pteridosperms. 
It is this view that the writer wishes to counter. It is to her in¬ 
credible that such ancient plants as Cordaites could have retained 
a catkin-like brachyblast which in its entirety might be regarded 
as homologous with the meriphyll of a Zygopterid Fern and that 
the parts really represent obsolete meriphytes. 
In turning to the insertion of the microsoroma or pollen-bearing 
apparatus we seem to have secured new light from the comparison 
of the so-called “stamen" of Cordaites , Taxus, etc., with the sporan- 
gial apparatus of the Psilophytales. In both, the soroma is radially 
symmetrical and terminal on a simple stalk-like body. Those of the 
older members of Ginkgoales appear to resemble Cordaites. We have 
instances carefully worked out of the abortion of certain sporangia 
of the terminal cluster in Ginkgo 1 giving the dorsiventral type of 
Ginkgo bilob a. The same phenomenon occurs in the passage from 
the radial symmetry of T axus to that of the dorsi ventral symmetry 
of Torreya 2 and Cephalotaxus. Such changes prepare us for the type 
found in Araucariaceae and the more or less peltate form found in 
Juniperus and other Conifers. The Psilophy tales prepare us for a 
transition from a radially symmetrical axial structure to a lamella. 
It seems to the writer to be reading complexity into simplicity to 
fail to accept the microsoromata and the megasoromata (seeds) as 
inserted directly upon axes. If this is recognized to be the universal 
condition in Sahni's Stachyosperms to what does the condition point ? 
The Stachyosperms are not members of the same series as the Ferns, 
nor of the Pteridosperms, Cycadophyta nor Angiosperms. They are 
Meiophylls and not Meriphylls—to use the nomenclature of the 
earlier part of this discussion. They probably have some kinship in 
the remote past with the Cryptogamic Meiophylls and their resem¬ 
blances to Cycads in their seed must be due either to the seed having 
originated before the distinctive types of foliage leaf were differen¬ 
tiated or possibly are due to homoplasy. 
Sahni 3 and Sprecher 4 have shown that the seed of Ginkgo has 
1 A. Starr, “The ‘Microsporophylls’ of Ginkgo,” Bot. Gazette, p. 134. 1910. 
2 Coulter and Laud, “Torreya taxifolia,” Bot. Gazette, p. 159. 1905. 
3 Sahni, “On Certain Archaic Features in the Seed of Taxus,” etc., Ann. 
of Bot. 34 , p. 117. 4 Sprecher, Le Ginkgo biloba (Geneve, 1907). 
