I TO 
Cavers . — On the Structure and 
again, so that the mother-cell contains four free nuclei, which move apart 
and take up equidistant positions near the periphery of the mother-cell. 
As shown by Farmer (1895), a disc of cellulose next appears near the 
centre of the mother-cell, and this becomes joined by ingrowths from the 
periphery, so that the four spores become partitioned off. The spore is 
at first pyramidal in form, having three flat sides meeting at the truncated 
apex of the pyramid and marking the surfaces where the spore was in 
contact with the other three cells of the tetrad. The coat is thin, but is 
differentiated into two layers, the inner being thin and homogeneous, the 
outer thicker, light brown in colour, and bearing externally numerous 
small papillae (PI. VII, Fig. 53). The spores begin to germinate whilst 
still enclosed within the capsule, each becoming divided up so as to form 
an ovoid mass of cells. In this respect Fegatella differs from the remaining 
Marchantiales, so far as known, though the same thing occurs in Pellia 
and in some species of Dendroceros. 
Elaters. 
The elongated cells which are mingled with the spore mother-cells 
remain sterile and give rise to the elaters. They continue for a considerable 
time to grow in length, their tapering ends passing in between the 
neighbouring cells, and then part of the protoplasm becomes arranged 
in a double spiral band on the inner surface of the cell-wall, whilst the 
remainder of the protoplasm, together with the nucleus, occupies the axis 
of the elater. Starch-grains are at first present, but these, together with 
the nucleus and the axial strand of protoplasm, eventually disappear, 
whilst the spiral band becomes thicker and at the same time assumes 
a brown colour. On tracing one of the turns of the spiral from one end 
of the elater it is usually seen to branch on its way towards the other end, 
and branches later, becoming united again ; hence each end of the elater 
shows a small loop, whilst at the middle there may be from three to five 
parallel bands (PL VII, Fig. 52 a). The typical fully-grown elater is 
spindle-shaped, from 0.15 mm. to 0.25 mm. in length. As a rule, one 
end is blunt and rounded, the other pointed and tapering, and there is 
generally a slight bend near the middle and often also at each end. 
The elaters often assume very curious shapes owing to the occurrence 
of branching. Nearly every capsule examined by the writer showed 
a certain proportion of branched elaters. The branching takes place 
at a relatively late period, after the spiral bands have been deposited 
but before they have assumed their final deep brown colouration, and 
after the spore-tetrads have become separated. In the hundreds of young 
sporogonia examined by the writer not a single case of branching was 
observed prior to the rounding-off of the spore mother-cells and their 
