“ The Origin of Gymnosperms ” 
76 
pith, as in Lyginodendron, the secondary wood being like that 
of Cordaitcs. The argument was that this character brought Cor- 
daites into relationship with the Cycadofilices, and that the Arau- 
cariese were so like Cordaites as to bring them into the same 
circle of affinity. But this evidence was insufficient. They had 
yet to demonstrate a relationship between the reproductive organs 
of Cordaiteae and Araucarieae. Finally, if they were not willing 
to accept the Fern-Cycad view of Araucarian affinity, what was the 
evidence for a Lycopod ancestry of the Conifers, or at least of the 
Araucarieae ? He would leave the question of habit out of consi¬ 
deration. Prof. Oliver had spoken of the resemblance of habit, but 
perhaps he had merely dangled that as a bait. Let them take the 
wood. There were obvious differences between the structure of 
the wood of Araucarieae and that of the Lycopods. The former 
had multiseriate bordered pits on the tracheid w r alls, while the 
latter had scalariform pits. This was of little importance because 
they all knew plenty of instances where there were transitions 
between scalariform and “ pitted ” tracheids in the same plant. 
Another point was the absence of the centripetal xylem, conspicuous 
in Lycopods, from the stem of the modern Araucarieae. But 
there was a considerable amount of transfusion tissue in the leaves 
of Araucaria and Agathis, and that might perhaps be homologous 
with centripetal xylem. But, as Dr. Scott had pointed out in “ The 
Old Wood and the New,” there was a strong tendency among plants 
which had adopted the method of producing centrifugal xylem by 
means of a cambium, to give up centripetal xylem altogether. So 
that this difference in the stems of the two groups was no evidence 
of want of relationship. As regarded the male cones, they could 
not point to any close agreement between the Araucarieae and the 
Lycopods, though as he had pointed out Cheirostrobus might be 
regarded as furnishing a connecting link. As regarded the female 
flowers the single sporophylls bore a strong resemblance to those 
of Selaginella and Lepidodendron. One striking point of difference 
was the fact that modern Lycopods did not produce any seeds. 
But they had Lepidocarpon, which fulfilled most of the characters 
of a true seed. Indeed it suggested comparison with the Araucarian 
seed because neither had a pollen-chamber and both were therefore 
of distinctly different type from those of the Pteridosperms and 
Cycads. This was an important argument in support of the view 
that the Lycopods might be the ancestors of the Conifers. He 
was afraid he might have been guilty of unbecoming dogmatism in 
the statement of his case, but he thought it important for the sake 
of discussion that each speaker should state his view as clearly and 
definitely as possible. He must reiterate his view that in any case 
the evidence for the derivation of the Conifers from Fern-like 
ancestors was wholly insufficient. 
[The Discussion rvas then adjourned.~\ 
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