VoL. XIV 
No. 5 
THE BRYOLOGIST 
SEPTEMBER 1911 
SOME STAGES IN THE DEVELOPMENT OF PELLIA 
EPIPHYLLA. 
(continued) 
HELEN E. GREENWOOD. 
On May 17 the former collecting ground was returned to. By 
this time the water of the river had receded several feet and grass 
and weeds had grown up on the bank to such an extent that it was 
difficult to find any Pellia, where earlier the bank had been covered 
for several feet with nothing else. The protective covering of the 
taller plants made the Pellia thalli so delicate and tender that they 
withered almost before they could be put into the fixing solution, 
which was done as speedily as possible. Since the last collection, 
the plants showed a considerable increase in size and the antheridial 
dots were more numerous and more prominent. They were situated 
all the way from the middle of the thallus nearly to the tip where 
they were clustered, showing a tendency to slant toward the growing 
point. On the drier parts of the bank the plants were a pale, yellow- 
ish green, reddish purple in the middle. Those in the moister situa- 
tions were of a much brighter green, of an even color throughout and 
were more fleshy in structure. Sections through this material showed 
antheridia that seemed to be fully matured, the several stalk cells and 
a great number of sperm cells being similar to Fig. 15. 
May 24 another locality was visited and Pellia epiphylla was 
found growing with great luxuriance on a moist shaded bank. The 
same difference in structure and appearance between the plants grow- 
ing in the drier and moister situations was noted. The microtome 
sections showed about the same stages of antheridial development as 
before. 
On May 29, the next collecting date, my notes only record the 
fact that the old brown plants show plainly in contrast to the new 
green shoots. Sections through this material show earlier stages of 
the antheridia than in the preceding. This is accounted for by the 
fact that this was collected from a drier location, while that of May 
24 came from a much more moist situation. 
The material collected June 7 showed nothing new or different. 
Sections made from plants collected on June 14, 1909, showed the 
same well formed antheridia but material gathered on the same date a 
year later, June 14, 1910, brought out some interesting comparisons 
and also for the first time, showed the presence of archegonia. On 
this latter date two sets of plants were gathered which were growing 
The July Bryologist was issued July 31st. 
