THE ORIGIN OF THE SEED-PLANTS 55 
ridosperms themselves, the most primitive known Seed-plants, were 
descended from the Ferns. 
Although it was pointed out that the stock from which the , Seed- 
Ferns” were derived was still unknown, and might well have differed 
widely from any group of Ferns with which we were familiar 1), yet the 
general idea of a Fern-ancestry was favoured. 
Zeiller, with excellent judgment, stated the position more cautious- 
ly. After pointing out how tempting is the idea of deriving the Cycads, 
through the Pteridosperms, from the Ferns,he showed that we could 
not regard such a filiation as established, firstly because the necessary 
link of heterosporous Ferns was missing, and secondly because in the 
Lower Carboniferous and Devonian the Pteridosperms were, as he 
thought, largely preponderant over the Ferns. He added that we could 
only infer a probable community of origin ?) 
Subsequently Zeiller seems to have been more impressed by the Fern 
-affinities of the early Seed-plants, for he said, in 1907, that „it is im- 
possible not to be struck by the close relations (liens) which exist bet- 
ween these „Seed-Ferns’” and the true cryptogamic Ferns,not only 
from the point of view of their external appearance, but from the point 
of view of their anatomical structure and even of the constitution of 
their organs of fructification.”” 3) At that time he even suggested that 
„heterosporous Ferns might have existed at a remote epoch and have 
given rise, by way of inverse modifications, on the one hand to Pteri- 
dosperms, on the other to isosporous Ferns.” ®) 
Whatever we may think of this suggestion, it shows that Zeiller was 
at that time prepared to derive the , Seed-Ferns” from an ancestry ac- 
tually superior to the typical Cryptogamic Ferns. 
Dr. Kıpston, in 1906, stated the position in words which appear per- 
fectly just, and anticipate the conclusion at which the present writer 
has arrived. He said 5): The Cycadofilices [Pteridosperms] are un- 
1) Studies in Fossiel Botany, Vol. I1, 2nd edition, p. 645. 
2) ZEILLER, „Une nouvelle Classe de Gymnospermes; Les Ptéridospermes, Re- 
vue Générale des Sciences, Aug. 30, 1905, p. 726. 
3) ZEILLER, „Les Végétaux Fossiles et leurs Enchainements,’’ Revue du Mois, 
Feb..10, 1907, p: 18. 
4) ZEILLER, L.c., p. 20. 
5) R. Kıpston, „On the Microsporangia of the Pteridospermeæ, with remarks 
on their relationship to existing groups,’ Phil. Trans. Royal Society, B. Vol. 
CXCVIII, 1906, p. 441. 
