470 



SCIENCE 



[N. S. Vol. XXV. No. 638 



SPECIAL ARTICLES 



RECENT DISCUSSIONS OF THE ORIGIN OF 

 GYMNOSPERMS ^ 



The discovery a few years ago by Pro- 

 fessors Scott and Oliver" of the relation of 

 the Paleozoic seeds known as Lagenostoma to 

 the stems of Lyginodendron, in itself perhaps 

 the most important contribution of paleo- 

 botany to botany that has ever been made, 

 appears to have inaugurated an era of specu- 

 lation in England during which the ferns 

 seem to be in danger of almost total elimina- 

 tion, if one may judge from some of these 

 recent contributions to the literature. Pro- 

 fessor Seward even bringing forward the 

 Lycopodiales as the ancestors of the Arau- 

 cariese and necessarily the balance of the Con- 

 iferales as well, as if to relieve the dwindling 

 Paleozoic Filicales from the burden of stand- 

 ing godfather to too many modern lines of 

 descent. 



While yielding full appreciation of the re- 

 markable discoveries so admirably worked out 

 in connection with the Pteridosperms, it seems 

 to the writer that the present is an opportune 

 time for recalling that threadbare maxim ' to 

 make haste slowly,' for while we observe a 

 laudable conservatism when it comes to a 

 mere ' impression,' a ' structure ' seems to be a 

 peg on which it becomes immediately neces- 

 sary to hang a theory. 



Aphlebiae may indicate pteridospennous 

 affinity as Professor Oliver has intimated, 

 and exannulate sporangia may also suggest, to 



' Oliver, F. W., ' The Seed, a Chapter in Evolu- 

 tion,' Pres. address to Botanical Section, Brit. 

 Assn. Adv. Sci., York, 1906. Arber, E. A. Newell, 

 ' On the Past History of the Ferns,' Ann. of Bot., 

 Vol. XX., pp. 215-232, July, 1906. 'The Origin 

 of Gymnosperms at the Linnean Society ' ( a dis- 

 cussion by Oliver, Scott, Arber, Seward, Weiss, 

 Worsdell and others). New Phytologist, Vol. V., 

 pp. 68-76, 141-148, 1906. Seward, A. C, and 

 Ford, Sibille, O., ' The Araucarieae, Recent and 

 Extinct,' Phil. Trans. Royal Soc. London, B, Vol. 

 198, pp. 305-411, 1906. 



•Scott, D. H., and Oliver, F. W., 'On the 

 Structure of the Paleozoic Seed Lagenostoma 

 Lomaxi, with a Statement of the Evidence upon 

 which it is Referred to Lyginodendron,' Phil. 

 Trans. Royal Soc. London, B, Vol. 197, pp. 193- 

 247, 1904. 



some, that the Eusporangiate ferns are ab- 

 sent in the Paleozoic, although this latter 

 view is a rather sweeping generalization from 

 Mr. Kidston's Orossotheca Hmninghausi and 

 Miss Benson's Telangium Scotti. One ia 

 tempted to inquire whence came these struc- 

 tures? Were they evolved among the Pteri- 

 dospermse? or rather do they not furnish 

 another illustration of what Mr. Worsdell 

 styles the grain of truth which underlies Pro- 

 fessor Seward's discussion, that " All groups 

 of plants shewed the same organs because they 

 had inherited them from common ancestors." 

 While the presence of Aphlebia-Wke, organs 

 and exannulate sporangia may eventually be 

 found to characterize the Pteridospermse, 

 they may with safety be considered to also 

 characterize some of those members of the 

 Filicales from which the Pteridospermse took 

 their rise. While I would not press the exist- 

 ing terminology of the Filicales too closely 

 upon the generalized forms of the Paleozoic 

 any more than I would consider the mammal 

 Phenacodus a horse or a cow, still in our 

 endeavor to get away from a too rigid termi- 

 nology we are in danger of going too far in 

 the opposite direction, and while it may per- 

 haps be well to set the early Filicales apart 

 under an ordinal name, that of Primofilicea 

 (personally I would prefer Eofilicales), it 

 savors somewhat of Saporta's Pro-Gymno- 

 spermae. Mr. Arber, however, seems to limit 

 the proposed term to the Leptosporangiate 

 Paleozoic ferns or their immediate ancestors 

 so that the group might equally well be termed 

 the Primo-Leptosporangiatse, in fact his dia- 

 gram (Ann. of Botany, fig. 1) shows that he 

 ' does not consider the evidence for the exist- 

 ence of the Eusporangiatae entirely satis- 

 factory ' until we come down to so compara- 

 tively recent a period as the Tertiary. The 

 writer feels very strongly that the future will 

 show this view to be a reactionary one. Per- 

 sonally I place more reliance on the re- 

 semblance of the ' frond genera ' Tceniopteris, 

 DancBopsis, etc., to modern forms, especially 

 as the fructifications are known in several 

 instances, than I do upon the suggestion that 

 these latter may be the sporangiate organs of 

 the Bennettitese the descendants of the Paleo- 



