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Fig. 2. Verrucaria nigrescens on rock. 
cies abundantly. The latter was also growing abundantly all the way up the 
trunk, nearly to the top, and also on some of the larger branches. A moss 
was also growing rather sparingly three-fourths of the way up the trunk of 
the tree. It was impossible to make a minute study of the whole trunk of 
the fallen tree, but an area thirty by one hundred cm., and containing some 
areas of lichens and mosses which were carefully located, was marked 
on the bark for future detailed study of succession. Two other areas were 
marked in the same manner, using small nails and cord, and making similar 
records of conditions within the areas. The study of rate of decay of this 
tree and others similarly studied, with observation of successions of plants 
upon them will surely be interesting and it is hoped may also contribute some 
data of value. In all such studies, specimens of the plants of each succes- 
sion will be carefully preserved. 
For the fifth study of the second series, a limestone rock was selected 
one-third meter square and eight cm. thick, lying flat on the ground in the 
shade and densely covered on the upper surface with Grimmia apocarpa 
Fig. i. A portion of the surface of the rock was chipped off, one-half to two 
cm. deep, so that any succession upon the chipped surface must be a pri- 
mary one. Study number seven is a similar limestone rock, but standing 
nearly perpendicular, nearly all above ground, and covered on the exposed 
sides and edges with the lichen, Verrucaria nigrescens. Fig. 2. Half of 
the surface was chipped in the same manner as in study number five, so 
that the rate and manner of invasion and ecesis may be studied. 
Other studies were made of lichens and mosses on ledges of rocks and 
on large and small boulders in varying conditions of environment, but enough 
has been recorded to illustrate the methods employed, 
Miami University. Oxford, Ohio. 
