346 
F. Cavers. 
means of the columella, the sterile cells, and the green tissue, and 
their rapid development is obviously due, as pointed out by Goebel 
(10) to these favourable arrangements for their nutrition. The sterile 
cells of A. Icevis are thickened along two opposite sides of the wall, 
which in some cases even shows distinct spiral thickening bands. 
The latter are well developed in Dendroceros and in certain species 
formerly included in Antlioceros , but now transferred to Campbell’s 
new genus, Megaceros. There can be little doubt, from actual 
observation, that even in A. Icevis the sterile cells perform, as their 
final function, some service in aiding spore-dispersal by means of 
hygroscopic movements. For some time the surrounding tissue of 
the thallus, into which the bulbous foot penetrates deeply and 
sends haustorial outgrowths of its outer cells, keeps pace with the 
growth of the sporogonium and grows up as a sheath, which is 
eventually broken through at the tip. The capsule reaches a 
length of as much as four inches in some species, giving fruiting 
patches of the plant the appearance of fine grass, and continues to 
grow for months. In germination, the spore-contents usually give 
rise to a longer or shorter germ-tube, at the end of which a cell- 
mass is formed, but sometimes the tube is suppressed ; in any 
case the cell-mass soon shows an apical cell, rhizoids, mucilage 
slits, and apical branching. 
In Dendroceros , the plant-body is distinguished into a thick 
and usually broad midrib with one-layered lateral wings, which 
are folded and often regularly lobed, showing an approach to the 
Fossombronia type with distinct leaves. Some species are 
definitely foliose, and in D. foliatus, discovered by Spruce (33), 
large hood-like structures are developed from the “ middle lohes ” 
formed in branching, in addition to smaller hidden appendages 
which represent the ordinary lobes or leaves. As in Anthoceros 
there are iVosfoc-cavities, and in some species large intercellular 
cavities in the midrib, giving the latter an areolated appearance 
like that of a Marchantiaceous thallus. The development of this 
genus has been chiefly worked out by Leitgeb and by Campbell 
(3). The apical cell is semi-circular, segments being cut from it 
in a single series. The antheridia are solitary, large, and long- 
stalked the stalk is coiled up within the cavity, the roof of the 
latter projecting strongly above the surface of the thallus. The 
sporogonium on the whole resembles that of Anthoceros , except 
that the archesporium extends downwards nearer to the foot and 
often remains in parts only one cell thick, the sterile cells becoming 
