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from one another in such a way that in a thin section we seldom see 
the four divisions in one plane and so they appear instead to be three 
lobed. In the former, the spiral thickenings in the walls of the 
elaters are very faint but in the latter these are plainly marked and 
the contrast in size between the fixed and free elaters is evident, the 
former being much larger. 
Before passing on to the later stages, attention should be called to 
the flattened cells arranged in longitudinal rows in the stems of .the 
sporogonia (figs. 39, 40, 41, 43, 44) so characteristic of 
No further collecting was done until Nov. 21. The weather had 
been sufficiently mild to melt the two light snows that had fallen 
earlier in the month and the plants did not seem to be at all frozen. 
The involucres fitted so tightly over the little cavities in which the 
capsules lay that it was difficult to tell at the first glance whether 
there was a capsule enclosed or not. The capsules were very vari- 
able in size and on the whole seemed smaller than those collected in 
the latter part of September and October. No four-lobed spore 
mother cells were to be found now, but in their places were the fully 
formed oval spores (fig, 44). Evidently the formation of the spores 
from the four-lobed spore mother cells occurs in the latter part of 
October or the first part of November,^ 
Sections through capsules collected Nov. 27 showed that not only 
have the spores been formed but that cell division has already begun 
to divide each of them into a multicellular body, i.e. the first stages 
in germination have already taken place (figs. 45 and 46a, b, c,) some 
of the spores are two celled, others four celled (46a), while others 
have each of the central cells divided again (46b). The walls of the 
spores seem to be very thin. 
On the next collecting date, Dec. 29, the ground was covered 
with quite a thick coating of snow, so Pellia epiphylla could only be 
found in a few bare spots and then the ground was frozen so that the 
plants had to be scraped off with a knife Each thallus was almost 
black and thin, dry and papery. The capsules were so shrunken 
down and hidden under the tightly closed involucres that it was 
necessary to look carefully to find them. The plants lay in a closed 
tin box over night in a fairly warm room and so lost their papery 
character, becoming rubbery instead. The next morning the capsules 
still seemed much shrunken but as soon as they were placed in the 
fixing solution, they expanded to their natural size. Vertical sections 
1. This process of cell division has been described by Dr. Davis, as follows: (Nu- 
clear studies in Pellia, B. M. Davis, Ann. of Bot. 15:247). 
“The. cell wall laid down after the first mitosis separates the lobes of the spore 
mother cell into pairs which lie at an angle to one another, if not perpendicular * * * 
a cell plate appears in the equatorial region of the spindle and is then shortly replaced 
by a cell wall and the division of the spore mother cells is complete.” 
