— 23 - 
Fig. i. Grimmia apocarpa on rock. 
Study number ten is a new sycamore ( Platanus occidentalis ) board 
replacing an old board in a section of board fence, whose other boards are 
abundantly covered with Placodium microphyllinum. The new board is the 
second from the top of the fence, and the rate of ecesis and something of 
direction of invasion may be noted. Another study similar to this, not yet 
numbered, is a new section of picket fence. The old pickets were covered on 
the north side with Lecanora varia, Physcia stellaria and some Parmelias 
and other lichens. The old pickets on either side of the new ones are now cov- 
ered with the same lichens as is also the horizontal framework of the fence 
to which the new pickets were nailed. This furnishes a most excellent oppor- 
tunity for observing the rate of invasion and ecesis. In both of these stud- 
ies. the dates of repairing were obtained from the owner and carefully 
recorded with other desirable data. 
The studies described above have to do with lichens only. Another 
series was begun, nearly all of which have to do in part or wholly with other 
plants. A few of these which concern lichens and mosses wholly or mainly 
will be of interest The first is as follows: A beech tree, one-half meter in 
diameter four feet from the base, fell in a storm July sixth, 1907. On the 
eighth of August, 1908, when the study began, the tree was perfectly sound 
toward the base, but showed some evidence of having rotted somewhat 
toward the top before it fell. There was a considerable amount of a fiyren- 
omycete on the upper one-fourth of the tree, and in all probability this fungus 
was growing before the tree fell. The tree was uprooted in such a way that 
the trunk was left intact so that no fungi could gain entrance at the base, and 
at the time of the first study, none were growing about the exposed roots. 
P armelia caper ata, Parmelia Borreri , and Trypethelium virens were grow- 
iug toward the base of the tree, the foliose ones sparingly, the crustose spe- 
