Evans: HeEpaTICAE OF PuERTO Rico 209 
grow at once into leafy shoots, the two-sided apical cell of a 
gemma becoming directly the tetrahedral apical cell of a new 
axis (FIGURE 15). Apparently a gemma never develops more than 
one leafy shoot. In their structure and germination the gemmae 
just described bear much resemblance to those of Radula compla- 
nata, of which we have an account by Cavers.* In both Radu/a 
and Cyclolejeunea, therefore, the gemmae of certain species produce 
gemmothallia, while those of other species fail to develop these 
remarkable structures. In C. Chitonia the gemmae are essentially 
like those of C. convexistipa and consequently retain their apical 
cells ; in many cases, however, they lack the unbranched marginal 
rhizoids. Germination in this species has not been observed. In C 
Peruviana the gemmae also retain their apical cells, but the region 
of attachment, through the division of the basal cells, is displaced 
toward the center of the gemma instead of being marginal. 
The gemmae of C. angulistipa differ in several important respects 
from those found in other species of Cyclolejeunea. As in C. 
accedens one of the marginal cells of a leaf projects beyond its 
neighbors (PLATE 10, FIGURE 10) and is divided by a wall into a 
stalk-cell and the mother-cell of the future gemma. The dividing 
wall, however, is at right angles to the surface of the leaf. The 
mother-cell then divides by a longitudinal wall into two equal 
cells situated side by side (FIGURE 11). In each of these cells the 
succeeding divisions go on independently. The cell first divides 
into an inner and outer cell by a wall at right angles to the longi- 
tudinal wall (FIGURE 12). The inner cell may or may not undergo 
a few irregular divisions. The outer cell behaves at once like an 
apical cell and continues to cut off segments for a considerable 
time (FIGURES 13, 14). The adult gemma is flat and ligulate in 
form, lying in the same plane as the leaf and parallel with its mar- 
gin (FIGURES 9,15). The stalk-cell is attached at the bottom of a 
distinct depression, and the two basal cells are indistinguishable 
€xcept by their position. If a plane is passed through the stalk- 
cell and at right angles to the surface of the leaf, it will cut the 
gemma into symmetrical halves, each of which has developed trom 
one of the two cells resulting from the original division of the 
mother-cell. The marginal cells are scarcely different from the 
others, but a few of them give rise to long spreading rhizoids lying 
* New Phytol. 2: (18). 1903. 
