- 96 — 
(fig. 49) showed the capsule wall to be generally two layers in thick- 
ness, the central space to be filled with the bunch of fixed elaters 
(which grow up from the base of the capsule), and the spores sur- 
rounded by free elaters scattered through the capsule cavity. 
Weather conditions prevented any collection being made in Jan- 
uary, but Feb. 7 found the temperature high enough, and the woods 
open enough for a collecting trip. The ground was quite thoroughly 
covered with a layer of ice and snow, but on just one tussock over 
the water’s edge the snow had melted and the plants of Pellia epiphylla 
had softened up so that they could be easily gathered. Some of the 
capsules were very large and nearly pushed out from under the in- 
volucres, looking as if sufficiently encouraged by warm weather they 
would shed their scores very soon. Vertical sections through these 
capsules show the spore cavity to be much crowded with spores, the 
elaters being pressed into a small space (fig. 50). 
The next collection was made on March 13. No change had 
taken place in the contents of the capsule (fig. 51). Vertical sections 
through the spores show almost exactly the same condition as those 
collected Nov. 27. The same figures (46a, b, & c.) represent these 
exactly. Evidently the spores are fully formed in November, and 
the intrasporal development so characteristic of Pellia epiphylla is com- 
pleted by the last of November. Therefore the spores must remain 
in a dormant condition over winter from November until they are 
shed in the following April. 
On April 24, the few capsules not already opened were collected. 
They were so sensitive to heat that as soon as they were placed in 
the paraffine oven and the temperature began to rise toward the melt- 
ing point, the four valves split open from apex to base curving tightly 
back against the seta and the spores were scattered through the fluid. 
The sections, therefore, were very fragmentary, being composed 
mainly of the capsule with the tuft of fixed elaters fastened securely 
to it and varying amounts of spores and free elaters scattered about 
over the sections. None of the spores were sectioned through, only 
outside views being presented. The spores are oval in shape, the 
outer wall being marked by irregular ridges or thickenings. 
This brings us back to the last of April, the point where we 
started, and completes the year’s record of the stages of the develop- 
ment of Pellia epiphylla. 
SUMMARY. 
1. Pellia epiphylla grows in shaded locations on damp soil in 
swamps and bogs, on moist roadsides, or on the banks of streams. 
2. The plant body is a slightly fleshy thallus, oblong, more or 
less sinuate, lobed or forked, the shape being modified according to 
the way it is crowded by other plants, an average size being from 
about a half an inch in width to an inch or an inch and a half in 
length. 
