DISTRIBUTION AND RELATIONSHIPS OF THE CYCADEOIDS 1 69 
rated by such a great lapse of time, the Gnetum and cycadeoid seeds show 
some pecuHar resemblances pointed out by Emily M. Berridge and Mrs. 
Thoday (see fig. 5). As Seward well says, it would be "rash" to hold 
such resemblances without phylogenetic significance. So also the details 
of sporogenesis may merely tend to parallel those of angiosperms, and may 
thus be deceptive — illusory, as Berry thinks the primitiveness of the mag- 
noliaceous flower to be. Nor is it necessary to assume that none of the 
cycadeoids advanced beyond a motile antherozoid stage. This view I was 
quite the first to put forward strongly, and must retract. The negative 
view alone is permissible as a hypothesis.* 
In the embryogeny is perhaps found the very strongest evidence for 
dicotyl derivatiofi from gnetaleans. W. P. Thompson observes much 
similarity, and some differences which may yet prove fundamental; but 
the subject is discussed by one of my colleagues. 
So far as regards the gnetalean wood, it must be urged once more that 
the vessels have been held to have peculiarities, and that the extent of 
parallel development since the Jurassic cannot yet be fairly estimated. 
W. P. Thompson says the vessels "should be removed from all discussions 
of the angiosperms." If so, then, similarly, the rays. The foliage of 
Gnetum Gnemon is of a peculiar netted type with a striking fineness of mesh 
not so very dissimilar from that of the laurel-leaf magnolia. Netting, 
however, probably developed progressively in the seed plants, and could 
as readily accentuate in pinnate cycadeoid blades, either primitively or 
secondarily netted. If the net is primitive in Gnetum, it can be primitive 
in the cycadeoids. If it resulted from separation, or alternant elision of the 
pinnate veins, with invasion of the marginal net in an earlier Gnetum, 
leading towards oleanders and magnolias, the same development could go 
on in cycadeoids. There, too, a real basal form is recognized in the fern- 
like Taeniopterid leaves of the flower-bearing Williamsoniella. That net 
venation was very anciently and widely present in the Cycadophytes is 
indicated by the fern-like mesh in the pinnules of the Indian Dictyozamites, 
one of the stereotyped Liassic cycadeoids. 
To continue, W. P. Thompson, in concluding one of his studies of 
gnetaleans, quotes an abbreviated statement of Scott on the "claim" of a 
cycadeoid-angiosperm ancestry as resting simply on three points — strobilar 
organization, fruit-enclosed seeds, and the exalbuminous nature of these. 
^ Stefanie Herzfeld emphasizes my own observation of conductive nucellar tissue in 
Cycadeoidea as evidence of zooidogamic fertilization. And that this mode was formerly more 
or less widespread amongst the gymnosperms must be beheved. Evidently, then, there is 
need to have a care in excluding such a mode from the cycadeoids. But it may be noted 
that the exact comparative study bearing on this point is scarcely made, while the object 
here is mainly to state the case theoretically. The zooidogamic type of fertilization must 
have disappeared mostly as the modern angiosperms arose, or mainly in the interim between 
the Rhaetic and the Cretaceous. So that in this time of great change amongst the cycadeoids 
as well it seems unlikely that they continued more primitive in this respect than conifers. 
