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SCIENCE 



[N. S. Vol. XXXIV. No. 876 



iuated independently in at least three of 

 the great phyla of vaseiilar Cryptogams, 

 and originally, no doubt, the same stro- 

 bilns contained both macro- and micro- 

 sporangia, as was the case in CaJamostacJiys 

 Cashca)m; in the strobili of most Lepido- 

 deudracea?, and as is still the ease in the 

 strobili of SdagineUa and in Isoetes. 

 Even in the existing heterosporous Fili- 

 cinese, micro- and maerospores are found 

 on the same leaf and on the same sorus; 

 and though in the higher Cryptogamia and 

 the lower Phanerogamia there may have 

 been a tendency to an iso-sporangiate con- 

 dition, yet, as the two kinds of spores are 

 obviously homologous in origin, nothing is 

 more natural than an occasional reversion 

 to a heterosporaugiate fructification. Thus 

 in the group of Gymnosperms we have 

 many instances of the occurrence of so- 

 called androgynous cones. In 1891, at the 

 meeting of the British Association in 

 Leeds. I described such amphisporangiate 

 cones which occurred regularly on a Pinus 

 Thunhergii in the Eoyal Gardens of Kew, 

 and only this spring I was able to gather 

 several hermaphrodite cones of Larix 

 Europea. They have, of course, been ob- 

 served and described by manj^ authors for 

 a variety of Gymnosperms. "What more 

 likely than that many extinct Gj'mno- 

 sperms may have developed heterosporau- 

 giate fructifications? It is not necessary, 

 therefore, to fix on one group of ancestors 

 for the origin of all existing Angiosperms. 

 Indeed, the great variety of forms, both of 

 vegetative and reproductive organs, which 

 we meet with in the Angiosperms, not only 

 to-day, but even in the Cretaceous period, 

 in which they first made their appearance, 

 warrants, I think, the belief in a poly- 

 phyletic origin of this highest order of 

 plants. It is no doubt true, as Wieland 

 points oi;t "that the plexus to which Cy- 

 cadoidca belonged, as is the ease in everv 



highly organized plant type, presented 

 members of infinite variet.y," and, indeed, 

 so far as the vegetative organization goes, 

 we know alread.y, through the labors of 

 Nathorst, of siich a remarkable form as 

 WiclandicUa angustifolia, while Wieland 

 has shown us a further tj'pe in his Mexican 

 ^YiUiamsonia. Nevertheless, these diverse 

 forms all agree in the structure of their 

 gynecium, the particular organ which is 

 not so easy to bring into line with that of 

 the Angiosperms. 



I am quite alive to, though somewhat 

 sceptical of, the possibility of a direct de- 

 scent of the Ranales from the Cycadoidefc, 

 but my hesitation in accepting Arber and 

 Parkin 's view of the ancestry of the Angio- 

 sperms is enhanced bj- the consideration 

 that it seems ahuost more difficult to derive 

 some of the apparent!}' primitive Angio- 

 sperms from the Ranales, than the latter 

 from Cyeadoidea. Indeed, this common 

 origin of Angiosperms from the Ranalian 

 plexus will, I feel sure, prove the stum- 

 bling-block to any general acceptance of 

 the Arber-Parkin theorj^. It is easy 

 enough to assume that all Angiosperms 

 with the unisexual flowers have been de- 

 rived by degeneration or specialization 

 from forms with hermaphrodite flowers of 

 the primitive Ranalian type, but unfortu- 

 nately some of these degenerate forms pos- 

 sess certain characters which appear to me 

 to be iindoiibtedly primitive. 



It is difficult for those who accept 

 Bower's view of the gradual sterilization 

 of sporogenous tissue not to regard the 

 many-celled archesporium in the ovules of 

 Casuarina and of the Amentales as a primi- 

 tive character, and though, as Coulter and 

 Chamberlain point out, this feature is 

 manifested by several members of the Ra- 

 nunculaeete and Rosacea?, as well as by a 

 few isolated Gamopetalte, its very wide- 

 spread occurrence in the Amentales seems 



