September 11, 1914] 



SCIENCE 



365 



has been added to what is already seen 

 normally each year in L. inundatum. And 

 this mode of life of Phylloglossiim begins, 

 as Thomas has shown, with its embryo. 

 This appears to me to be a rational explana- 

 tion of the "protocorm" of Phylloglossum; 

 but it robs the plant of much of its theo- 

 retical interest as an archaic form. 



The phylum of the Sphenophyllales was 

 originally based on certain slender strag- 

 gling plants of the genus Sphenophyllum 

 found in the Paleozoic rocks; but appar- 

 ently died out in the Permian period. 

 Your native genera Tmesipteris and Psila- 

 tum were ranked by earlier botanists with 

 the Lycopods, but a better acquaintance 

 with their details, and especially the exami- 

 nation of numerous specimens on the spot, 

 indicated a nearer affinity for them with 

 the Sphenophyllales. It was Professor 

 Thomas who, in 1902, first suggested that 

 the Psilotaeeas might be included with the 

 Sphenophyllae in the phylum of the Spheno- 

 phyllales, and I personally agree with him. 

 Dr. Scott, however, dissents, on the ground 

 that the leaves are persistently whorled in 

 the sphenophylls, while they are alternate 

 in the Psilotaeeas; and while the former 

 branch monopodially the latter dichotomize. 

 But since both of these characters are seen 

 to be variable within the not far distant 

 genus Lycopodium, the differences do not 

 seem to me to be a sufficient ground for 

 keeping them apart as the separate phyla of 

 Sphenophyllales and Psilotales. Whatever 

 degree of actual relation we trace, such 

 plants as Tmesipteris and Psilotum are cer- 

 tainly the nearest living representatives of 

 the Sphenophyllese, a fact which gives them 

 a special distinction. The Psilotacese also 

 stand alone in the fact that they are the 

 only family of the Pteridophytes in which 

 the gametophyte is still unknown. They 

 produce spores freely, but there the story 

 stops. Any young Australian who hits 



upon the way to induce these recalcitrant 

 spores to germinate, and to produce proth- 

 alli and embryos, or who found their proth- 

 alli and embryos in the open, would have be- 

 fore him a piece of work as sensational as 

 anything that coiild be suggested. Further, 

 I am told that Tmesipteris grows here on 

 the matted stumps of Todea harbara. I 

 shall be alluding shortly to the fossil Os- 

 mundaccEe. May we not venture to fancy 

 the possibility of some fossil Osmunda be- 

 ing found which has embalmed for us 

 among its roots a Mesozoie or even a Ter- 

 tiary Sphenophyll ? And thus a link might 

 be found between the Paleozoic types and 

 the modern Psilotacese, not only in time, but 

 even in character. 



We pass now to the last phylum of the 

 Pteridophyta, the Filieales. I am bound to 

 say that for me its interest far outweighs 

 that of others, and for this reason: that it 

 is represented by far the largest number of 

 genera and species at the present day, while 

 there is a sufficiently continuous and rich 

 succession of fossil forms to serve as an effi- 

 cient check upon our comparative conclu- 

 sions. 



Since 1890 it has been generally accepted 

 that the Eusporangiate ferns (those with 

 more bulky sporangia) were phyletically 

 the more primitive types, and the Lepto- 

 sporangiate (those with more delicate 

 sporangia) the derivative, and in point of 

 time later. The fossil evidence clearly up- 

 holds this conclusion. But, further, it has 

 been shown that the character of the 

 sporangium is merely an indicator of the 

 general constitution of the plants in ques- 

 tion. Where it is large and complex, as in 

 the Eusporangiates, all the apical segmenta- 

 tions are, as a rule, complex, and the con- 

 struction of the whole plant relatively bulky. 

 Where the sporangium is delicate and rela- 

 tively simple all the apical segmentations 

 follow suit, and the construction of the 



