. The theory of evolution in the light of facts. bility bordering on certainty, beassociated with fern leaves and fern Oliver and Scottparticularly andStur previously havedone meritoriousservice in the deter-mination of thismost important dis-covery. Figs. 16 and 17show a fern stemand the seed belong-ing thereto, whichin exterior formresembles a hazel nut. The new group of theseCarboniferous Gymnosperms received the provisionalnames of Pteridospermen, seed-plants with fern-like foliage. They are not intermediate forms sincethere are to-day Gymnosperms with fern-hke leaves, the
. The theory of evolution in the light of facts. bility bordering on certainty, beassociated with fern leaves and fern Oliver and Scottparticularly andStur previously havedone meritoriousservice in the deter-mination of thismost important dis-covery. Figs. 16 and 17show a fern stemand the seed belong-ing thereto, whichin exterior formresembles a hazel nut. The new group of theseCarboniferous Gymnosperms received the provisionalnames of Pteridospermen, seed-plants with fern-like foliage. They are not intermediate forms sincethere are to-day Gymnosperms with fern-hke leaves, the sago or fern palms. We observe then, in the history of the plant world,that with the progress of palaeontology the systematic ^ Compare with this the instructive statement by F. W. OKver: Ueberdie neuenideckten Samen der Steinkohlenform, in the Biol. Zentralhlatt, 1905,p. 401 ; Lotsy: Vorträge über Bot. Stammesg., II, p. 706 ; Potonie, inthe collected work. Die Natürlichen Pflanzenfamilien, published by Englerand Prantl: I, Part iv, p. Fig. 17.—The seed (L. Oldhamianum, Fig. 16) isenclosed in a husk which is covered withglands. {After Biol. Zentralhlatt.) RESULTS OF PAL^EONTOLOGICAL RESEARCH 59 groups of higher standing must be referred to an olderand older period. It is not long ago/ says Lotsy, that it was thought that the seed-bearing plantswere of comparativelyrecent origin and thatat least in the Coalperiod they were en-tirely absent/ Nowthe Cryptogams (non-seed-bearing plants)are not even concededpredominance in thelater Palaeozoic period(Fig. 18). Graduallythe Ferns, one afterthe other, showedthemselves to be seed-bearers, and it is difh-cult to say to whatnumber relatively thisalteration will will probably be alarge one. ^ Yet must we agreewith Gothans warning against over-hasty conclusions.^The true fern nature of a leaf is certainly onlybeyond all doubt when we find the spore heapson the under side of the fohage or elsewhere, sincethereby they ar
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