Origin of Seed-plants 209 
micropyles of the ovules were in a position to receive the pollen 
directly, without the intervention of a stigma. It is thus indicated 
that the Angiosperms sprang from a gymnospermous source, and 
that the two great phyla of Seed-plants have not been distinct 
from the first, though no doubt the great majority of known 
Gymnosperms, especially the Coniferae, represent branch-lines of 
their own. 
The stamens of the Bennettiteae are arranged precisely as in 
an angiospermous flower, but in form and structure they are like 
the fertile fronds of a Fern, in fact the compound pollen-sacs, or 
synangia as they are technically called, almost exactly agree with 
the spore-sacs of a particular family of Ferns—the Marattiaceae, a 
limited group, now mainly tropical, which was probably more promi- 
nent in the later Palaeozoic times than at present. The scaly hairs, 
or ramenta, which clothe every part of the plant, are also like those 
of Ferns. 
It is not likely that the characters in which the Bennettiteae 
resemble the Ferns came to them directly from ancestors belonging 
to that class; an extensive group of Seed-plants, the Pteridospermeae, 
existed in Palaeozoic times and bear evident marks of affinity with 
the Fern phylum. The fern-like characters so remarkably persistent 
in the highly organised Cycadophyta of the Mesozoic were in all 
likelihood derived through the Pteridosperms, plants which show an 
unmistakable approach to the cycadophytic type. 
The family Bennettiteae thus presents an extraordinary association 
of characters, exhibiting, side by side, features which belong to the 
Angiosperms, the Gymnosperms and the Ferns. 
ii. Origin of Seed-plants. 
The general relation of the gymnospermous Seed-plants to the 
Higher Cryptogamia was cleared up, independently of fossil evidence, 
by the brilliant researches of Hofmeister, dating from the middle 
of the past century’. He showed that “the embryo-sac of the 
Coniferae may be looked upon as a spore remaining enclosed in 
its sporangium ; the prothallium which it forms does not come to 
the light.” He thus determined the homologies on the female side. 
Recognising, as some previous observers had already done, that the 
microspores of those Cryptogams in which two kinds of spore are 
developed, are equivalent to the pollen-grains of the higher plants, 
he further pointed out that fertilisation “in the Rhizocarpeae and 
1 W. Hofmeister, On the Germination, Development and Fructification of the Higher 
Cryptogamia, Ray Society, London, 1862. The original German treatise appeared in 
1851. 
2 Ibid. p. 438. 
D. 14 
