170 THE EVOLUTION OF CONTINUITY 



voted to showing that one class of plant, the Phanserogam, 

 came suddenly into existence, not through derivation 

 from any previously existing terrestrial plant-form, but 

 from a marine type of already fixed Continuity. If this 

 can be shown to have happened with the Phanaerogams, 

 it may also reasonably have occurred with respect to 

 Pteridophytes and Bryophytes. 



Regarding the question solely in the light of Continuity-evolution, 

 we may conclude that the Algae and Fungi have originally a discon- 

 tinuously multicellular derivation, rather than that they share a 

 common primitive filamentous ancestry. 



It is difficult to say anything about the Moss's evolution, because 

 we cannot classify the Moss's Continuity. The protonema of the 

 Moss is of filamentous Continuity, but the plant arising from it is 

 clearly of a higher form. 



In Pteridophytes, for example in the Fern, and especially in the 

 Horsetail, we would detect direct derivation from a water-inhabiting 

 continuously zooidal type (or types), and not evolution from the 

 Bryophytes. There are no signs, past or present, suggesting that 

 Ferns have descended from Mosses, though much work has been done 

 to prove that they have done so. Professor Scott, in " The Evolution 

 of Plants," adopts the view that the Fern has an algoid ancestry in 

 which there was an alternation of generations as in the brown alga, 

 Dictyota ; that a water -inhabiting plant bearing spores was followed 

 by one of identical appearance bearing gametes ; and that the fern 

 plant corresponds to the former. He suggests that aerial environ- 

 ment improved the sporophyte, while need for water as a means for 

 fertilisation dwarfed and altered the gametophyte into the form of 

 a prothallus ; a process of degeneration. 



While recognising the high authority of Professor Scott, we ven- 

 ture to suggest that alternation of generations is not a safe guide in 

 tracing the evolution of terrestrial organisms, but that we should 

 rather turn to examine the species of Continuity the organism in ques- 

 tion exhibits. Our belief is that the Fern Individual has a marine 

 continuously zooidal derivation, and that the forerunners of the fern 

 plant and its prothallus were not similar but quite different, just as 

 a branching zooidal colony differs from its gonophore. There is, 

 however, no known type of zooidal colony which confirms our belief 

 though from the graptolite fossils it is clear that there existed in 

 the earliest ages zooidal colonies with a plan totally different from 

 existing ones, and peculiarly suggestive of fern structure. 



The Evolution of Phanerogams. 

 At the present time the tendency is to picture the 



