210 Evans: HepaTIcAE OF PUERTO RICO 
in the plane of the gemma. The two apical cells, which are of 
course marginal cells as well, are persistent and can easily be dis- 
tinguished at the ends of the gemma. Occasionally an unsym- 
metrical gemma may be observed, and this is usually caused by 
the arrested development of one of the apical cells. There is at 
present no evidence whatever that the adult gemmae are dorsiven- 
tral, a condition which is apparently found in C. accedens and C. 
convextstipa. 
Owing to the habitat of C. anvgulistipa —on rough bark — the 
marginal rhizoids are usually sufficient to hold the gemmae in 
place when they become separated from the parent plant ; some- 
times, however, a few supplementary rhizoids are produced. The 
germination does not always follow the same type. In cases 
which may be considered the more typical, one of the apical cells 
gives rise at once to a leafy shoot without the interpolation of a 
gemmothallium (FIGURE 16). In other cases a long strap-shaped 
gemmothallium is developed, which may or may not produce other 
structures of the same sort by proliferation (FIGURE 17). The 
growth of the gemmothallium is by means of a two-sided apical 
cell, and this is probably directly derived from the similar cell of 
the original gemma. When proliferation takes place the secon- 
dary gemmothallia may grow out from the apex of the primary 
one or from other parts of its margin. In C. angudistipa, there- 
fore, the two types of germination which are described above are 
both exhibited. 
The processes of vegetative reproduction in this species may 
be still further complicated. The gemmothallium, for example, 
may itself give rise to gemmae of the ordinary type, resembling in 
this respect the highly developed protonema or gemmothallium of 
Metzgeriopsis.* In other cases a leaf-cell may grow out into 4 
thalloid structure with a single apical cell, from which a leafy 
shoot eventually develops. This is doubtless an example of a 
protonema growing directly from a vegetative cell instead of from 
a spore and resembles the cases described and figured by Goebel.t 
A protonema of this type is scarcely to be distinguished by its 
appearance from a gemmothallium. 
a FCS Goebel, . Soa aps is a pl. 7. f- 72. 1887; also Schiffner, 
Oesterr. Bot. Zeits. 43: -f f 
} Flora, 92: 17. ee z, “ey 19. ae 
