Jantjabt 15, 1909] 



SCIENCE 



97 



The spore-fruit inherited from the pre- 

 ceding phylum undergoes many changes 

 and is often degenerated, and this some- 

 times involves the gametes themselves. 



This phylum is one of marked departure 

 from the general upgrade evolution in the 

 vegetable kingdom, and its successive 

 smaller phyla show increasing degenera- 

 tion in the structure of the plant body, 

 which in the rusts and smuts becomes ex- 

 cessive, while in some cup-fungi {Pezizales 

 and Eelvellales), puff-balls {Lycoper- 

 dales) and toadstools (Mymenomycetales) 

 the spore fruit is relatively very large. 



From the higher Protophyceae (prob- 

 ably near Coleochaetales) came the eighth 

 phylum— 



8. Bryophyta, in which the dominant 

 idea is the growth of the zygote into an 

 alternate, short-lived generation, the sporo- 

 phyte, and the consequent adoption of the 

 land habit. 



The two secondary phyla are Eepaticae 

 and Musci. 



From the lower Bryophyta (probably 

 near Anthocerotales) came the ninth 

 phylum— 



9. Pteridophyta, whose dominant char- 

 acter is the growth of massive roots and 

 broad leaves upon the sporophyte, render- 

 ing it long-lived and independent, and re- 

 sulting in the postponement of spore 

 formation. 



It must be noted here that I use the 

 term Pteridophyta in the narrower sense, 

 limiting it to ferns (Filicinae) and ex- 

 cluding lycopods and horsetails. The in- 

 coming of heterospory in some ferns is a 

 significant fact. 



From the lower Pteridophyta (probably 

 near Ophioglossales) came the tenth 

 phylum— 



10. Lepidophyta, in which the dominant 

 character is the long-lived, erect cylin- 

 drical stem of the sporophyte, which bears 

 massive roots below, is covered with many 



small scattered leaves, and terminates in a 

 strobilus of imbricated sporophyUs above. 

 From the lower Pteridophyta again 

 (probably near Ophioglossales) came the 

 eleventh phylum — 



11. Calamophyta, in which the domi- 

 nant character is the long-lived, erect, 

 cylindrical stem of the sporophyte, which 

 bears massive roots below, regularly 

 whorled leaves and branches, and termin- 

 ates in a strobilus of whorled sporophyUs. 



In the two preceding phyla, heterospory, 

 although present, has not yet become fixed. 

 In both the increased definiteness of the 

 strobilus is significant. 



From other lower Pteridophyta (near 

 Marattiales of Isoetales) came the twelfth 

 phylum — 



12. Cycadophyta, in which the dominant 

 idea is the uniform production of hetero- 

 spores in simple strobili of open sporo- 

 phyUs, upon the megaphyllous, spongy- 

 wooded sporophyte, and the permanent re- 

 tention of the megaspore in the sporan- 

 gium, thus forming the seed. 



I here include not only the cycads proper 

 {Cycadineae) , but also the much more 

 primitive "seed ferns" (Cycadofilices) , 

 the ancestral conifers (Cordaitineae), the 

 ancestral flowering plants (Bennetti- 

 tineae), and the maiden-hair trees {Gink- 

 goineae). 



From Cycadophyta came the— 



13. Gnetales, if indeed they are not to 

 be regarded as belonging to that phylum. 



The three genera are doubtless the sur- 

 viving remnants of former rather well de- 

 veloped secondary phyla, now nearly ex- 

 tinct.* 



From the Cycadophyta came the four- 

 teenth phylum — 



14. Strobilophyta, in which the domi- 

 nant idea is the development of definite, 



' Consult here Arber and Parkin's paper on the 

 Gnetales, in Annals of Botany, Vol. XXI. (1908), 

 p. 489. 



