— 99 — 
3. The thallus is composed o£ parenchyma cells bordered by an 
epidermal row of cells above and below, being abundantly provided 
with rhizoids. 
4. Pellia epiphylla is monoecious, the antheridia being scattered 
along the middle of the thallus to the tip, while the archegonia are 
formed just behind the growing point. 
5. In this locality the spores are shed in the latter half of April. 
6. The old plants then die down and new shoots immediately 
spring out from the edges of these plants. 
7. Antheridia soon make their appearance on these new shoots. 
The early stages of antheridia should be looked for shortly after the 
middle of April. 
8. The mature stages of the antheridia may be found from the 
last of April through May and June. 
9. Archegonia may be found early in June. 
10. According to observations on material collected in 1909 and 
1910 fertilization does not take place until early July. As both these 
seasons were unusually dry, fertilization may normally occur in June, 
if the rainfall is heavier. 
11. After fertilization the embryo grows rapidly through July and 
develops into a pear-shaped body. 
EXPLANATION OF PLATE XV 
Fig. 41. Vertical section through small portion of capsule repre- 
sented in fig. 40, X 233. Capsule wall two layered. Lobed 
spore mother cells with nucleus near center, elaters still in nucle- 
ate stage. 
Fig. 44. Median longitudinal section through sporogonium. Coll. 
Nov. 21. X 55. 
Fig. 45. Portion of vertical section through capsule. Coll. Nov. 
27. X 55. 
Fig. 46 a, b, c. Vertical sections through spores from capsules. 
Coll. Nov. 27. X 330. Spores have already begun to divide 
into a multicellular body, i. e., the development of the gametophyte 
has already begun. Vertical sections through spores collected 
Mar. 13, have the same appearance. 
Fig. 47. Single elater X 55. 
Fig. 48. Portions of elaters X 330. 
Fig. 49. Median longitudinal section through sporogonium. Coll. 
Dec. 29. X 55. 
Fig. 50. Median longitudinal section through sporogonium. Coll. 
Feb. 7. X 55. 
Fig. 51. Median longitudinal section through capsule. ColL Mar. 13. 
X 55. 
