1 1 8 Bower— Is Eusporangiate or Leptosporangiate 
existence of a single initial cell in Phanerogams 1 , while in 
certain Thallophytes and Bryophytes no single initial is pre- 
sent : this point cannot therefore be accepted as having much 
weight. The presence of a single initial seems frequently to 
follow a less robust habit and a sharp curvature of surface of 
the growing-point. Plants of aquatic position are commonly 
of delicate texture ; most of the lower forms are more or less 
distinctively aquatic ; accordingly the presence of a single 
initial, though common in the lower forms, is not necessarily 
to be viewed as an indication of a lower affinity. 
(v) Again, some may see in the rootless condition of certain 
of the Hymenophyllaceae, evidence that these are primitive 
forms, which share this character with the sporophyte of the 
Mosses. This condition is reputed to occur in certain species 
of Trichomanes , but, as Giesenhagen has observed 2 , we are not 
yet in a position to state that these Ferns are really rootless in 
every stage, and in those species in which the seedlings have 
been seen, a root is present. But even if they were proved to 
be actually rootless at all stages of their life, the absence of 
roots might be a result of degeneration, as it undoubtedly is in 
Wolffia, or in the Utricularias described by Goebel 3 : it is not 
necessarily to be accepted as a primitive character. 
We have now reviewed those characters upon which the 
Bryophytic affinity of the Filmy Ferns may be based, and the 
most satisfactory character for purposes of comparison is the 
protonema. Against this, which as above pointed out, may 
be viewed as a more directly adaptive rather than as an 
ancestral character, is to be set the fact that the simpler Ferns 
are the only Leptosporangiate Vascular Cryptogams, and that 
living forms afford no clue as to any direct mode of origin of 
such simple sporangia 4 . Thus the comparison above dis- 
1 The most prominent example is the root of Heleocharis palustris. 
2 Flora, Oct 1890, p. 460. 
3 Ann. d. Jard. Bot. de Buitenzorg, vol. IX, p. 98. 
4 It is not necessary to dwell upon Prantl’s suggestion as to the origin of the 
Hymenophyllaceous sorus from some form like Anthoceros. A view which 
depends upon the conversion of the internal sporogenous layer into a number of 
superficial sporangia, without any evidence how such a conversion did or 
