The structure & development of the mosses and ferns (Archegoniatae) . ableextent the form of the protonema. This is well known to bethe case in Ferns. The very peculiar modifications observed in certain tropicalHepaticae, especially by Spruce and Goebel, should bementioned in this connection. In these forms the protonemais permanent and the leafy gametophore only an appendageto it. In ProtocepJialozia epheineroides, a species discovered bySpruce in Venezuela, the plant forms a dense branchingfilamentous protonema much like that of the true ]\Iosses,which it further resembles by having a subter
The structure & development of the mosses and ferns (Archegoniatae) . ableextent the form of the protonema. This is well known to bethe case in Ferns. The very peculiar modifications observed in certain tropicalHepaticae, especially by Spruce and Goebel, should bementioned in this connection. In these forms the protonemais permanent and the leafy gametophore only an appendageto it. In ProtocepJialozia epheineroides, a species discovered bySpruce in Venezuela, the plant forms a dense branchingfilamentous protonema much like that of the true ]\Iosses,which it further resembles by having a subterranean and anaerial portion. Upon this confervoid protonema are borne theleafy gametophores, which are small and appear simply as buds. no MOSSES AND FERNS CHAP. Among the other remarkable forms is Lejeunia metsgeriopsis, aJavanese species discovered by Goebel growing upon the leavesof various epiphytic Ferns. It has a thallus much like that ofMetzgeria, and like it has a two-sided apical cell. This thallusbranches extensively (Fig. 52, A), and propagates itself by. Fig. 52.—A, Lcjeicnia metzgeriopsis (Goebel), showing the thalloid protonema with terminal leafybuds (U), X 14 (after Goebel). B, Gemma of Cvlolejcunia Goebelii. numerous multicellular gemmae. This thallose condition is,however, only maintained during its vegetative to the formation of the sexual organs, the two-sidedapical cell of a branch becomes three-sided, as in the youngplant of other species of Lejeunia^ and from this three-sided IV THE JUNGERMANNIACE^E III apical cell a short leafy branch, bearing the sexual organs, isproduced.^ Considerable variety is exhibited by the leaves of theAcrogynae as to their form and position, but all agree in theiressential structure and early growth. The two lobes may beeither equal in size or unequal. In the latter case either thedorsal or ventral lobe may be the larger, when the leaves areoverlapping, as occurs in most genera. Where the dorsal halfis the
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